Shallow Water Areas Research Articles

Polygonum criopolitanum Hance Expansion and Its Effects on Overwintering Goose Populations in the Poyang Lake Wetland

Since 2003, Poyang Lake has been showing obvious signs of degradation due to its changed “river-lake” relationship with the Yangtze River. The water level of Poyang Lake decreases continuously in autumn. The distribution elevation of wetland beach vegetation is constantly moving down and the distribution range is constantly expanding. The Polygonum criopolitanum community expansion at 9–12 m elevation (Yellow Sea elevation, the same below) has resulted in a significant decline in areas of mudflat and shallow water, and a significant change in habitat structure for overwintering migratory birds. Combined with field investigation, controlled experiments and statistical modeling were conducted to simulate Polygonum criopolitanum growth at 9–12 m elevation to establish its growth curve, effective growth time, growth rate, and fast-slow turning point. Polygonum criopolitanum growth rate was fastest in the 12 m elevation zone, and reached a maximum in only 22 days. After that, growth rate slowed down and tended to stagnate. Maximum growth rate of Polygonum criopolitanum in 10 and 11 m elevation zones occurred on the 31st and 46th days, respectively. At the inflection point, the Polygonum criopolitanum biomass accumulation rate was fast, then it gradually slowed down until it stopped. Polygonum criopolitanum growth and development at 9–11 m elevation was highly consistent with the arrival of overwintering migratory geese. Polygonum criopolitanum expansion at 9–11 m elevation created fine habitat conditions and rich food resources for populations of Soybean Goose, White Goose, Swan Goose and Cygnet, which was the fundamental reason for the formation of the Duchang Migratory Bird Reserve after 2003. This study is of scientific significance for studies of wetland vegetation community distribution and the promotion of reserve management.

The effects of astronomically forced climate change on hemipelagic carbonate sedimentation in a tectonically active setting: the Albian Mioño Formation in Castro Urdiales (Cantabria, N Spain)

Our understanding of the stratigraphic expression of astronomically driven climate-change cycles in the Milankovitch frequency band has improved significantly in recent decades. However, several aspects have been little studied to date, such as the nature of the climatically regulated environmental processes that ultimately control cyclic sedimentation. Similarly, relatively little is known about the expression of Milankovitch cycles in successions accumulated in tectonically active basins. In order to fill this knowledge gap, the Albian hemipelagic deposits of the Mioño Formation exposed in Castro Urdiales (Basque-Cantabrian Basin) are studied herein. These deposits were accumulated during a rifting phase with strong tectonic activity. The sedimentological, petrographic and cyclostratigraphic analysis demonstrates that, despite the synsedimentary tectonic instabilities and some diagenetic overprinting, the hemipelagic carbonate alternation was astronomically forced 110.68–110.47 Ma. Seasonality fluctuations driven by precession cycles caused periodic (20 ky) variations in the rate of carbonate productivity (abundance of pelagic calcareous plankton and micrite exported from adjacent shallow-water areas) and/or siliceous dilution (terrestrially derived siliciclastic sediment supply and siliceous particle production by sponges). These variations resulted in the formation of marly limestone beds when annual seasonality was low (i.e., boreal summer at aphelion, winter at perihelion) and the accumulation of marlstones when seasonality increased (i.e., boreal summer at perihelion, winter at aphelion). The incidence of these processes increased and decreased in line with seasonality modulation by short-eccentricity cycles of 100 ky. In conclusion, this study shows that Milankovitch cycles can be reliably recorded in hemipelagic successions accumulated in tectonically active settings if sediment gravity flows or other disturbances do not affect autochthonous sedimentation.

LSPIV analysis of ship-induced wave wash

Ship-induced wave wash affects the hydromorphological and ecological state of rivers through various mechanisms. The direct proximity of the riverbank is usually the most exposed, as the hydrodynamic stresses are the highest in these shallow water areas. Contrary to the steady and almost still, natural flow conditions (i.e., no waves of anthropogenic source), shoaling and breaking of ship waves increase the hydrodynamic stresses by orders of magnitudes, having notable ecological consequences, and resulting in bank erosion as well. Due to the shallow water depths and temporary drying, conventional measurement techniques are no longer applicable in these areas. In this study, large-scale particle image velocimetry (LSPIV) is used to quantify the prevailing flow conditions. In the absence of ground truth data in the wave breaking region, a high-resolution computational fluid dynamics model—verified with field pressure and acoustic Doppler velocimetry data—is used for the cross-validation of the LSPIV results. The results underline the applicability of LSPIV for the hydrodynamic analysis of wave velocities in this special riverine swash zone, which is of key importance from the aspect of ecology and bank erosion as well.Graphical abstract

Ледокольный атомный флот как фактор развития Северного морского пути.

The successful development of the Northern Sea Route (NSR) implies the creation of a developed transport infrastructure, which should result in a significant increase in cargo turnover along the route. The article discusses the process of forming a modern atomic fleet as the basis for safe navigation, aimed at solving the important problem of further development of the Arctic transport system. In terms of navigation, the NSR is one of the most complicated and dangerous sea routes, which, in addition to its long length, is distinguished by the presence of shallow water areas located far away from the coast, and difficult ice conditions. The task of further increasing the cargo turnover cannot be solved without providing year-round navigation. Due to the harsh climatic conditions in the Arctic latitudes, year-round navigation is not feasible without an appropriate icebreaker support. As the atomic icebreaker fleet is already quite outdated today, it is necessary to put new icebreakers into operation. The purpose of the study is to identify problems in terms of raising one of the efficiency indicators of the NSR performance — cargo turnover, provided renovation of the icebreaker fleet as a factor, necessary for solving the tasks of successful functioning of the route. It was concluded that the commissioning of icebreakers is hindered by insufficient funding of the industry, but the main problem lies in the consequences of the crisis in Ukraine in 2014. As a result, the supply chains of shipbuilding were disrupted and sanctions against the Russian Federation were imposed. The situation has been exacerbated by the imposition of new unprecedented sanctions packages since the launch of the special military operation in February 2022. The practical significance of the study is that the conclusions drawn are aimed at the further NSR development. The rapidly changing international situation and the economic situation within the country determine the prospects for further research on the topic.

Выделение мод шумового источника в мелком море методом голографической интерферометрии в присутствии интенсивных внутренних волн

The results of a numerical experiment on approbation of the holographic method of mode selection in a shallow water area against the background of intense internal waves, which cause interaction of waves of a broadband sound source. An analysis of the resolution of modes and the restoration of their parameters has been carried out. It is shown that the effects of mode interaction do not lead to the loss of the identity of the mode characteristics of the signal.

Landscape Archaeology of Southern Mesopotamia: Identifying Features in the Dried Marshes

The landscape of the Mesopotamian floodplain is mainly structured by channel processes, including the formation of levees, meanders, scrollbars, oxbow lakes, crevasse splays, distributary channels, inter-distributary bays, and marshes. Moreover, several human-made features also form and shape this landscape, such as canals, roads, trenches, farms, and settlement sites ranging in size from villages to cities. A significant part of the Mesopotamian floodplain is covered by marshes, especially the southern region. These marshlands have thrived for thousands of years and are well known for their sustainable biodiversity and ecosystem. However, after the deliberate draining of the marshes in the 1990s, the areas have become dry and only small areas of shallow water and narrow strips of vegetation remain. Several kinds of archaeological landscape features have appeared on the surface and can be clearly identified in both ground surveys and with the use of remote sensing tools. This paper aims to determine the type and nature of the preserved archaeological features that appear in the landscape of the dried marshes and whether they are different from other features elsewhere in the Mesopotamian floodplain. An intensive ground survey was carried out in a selected area of the dried marshland, resulting in the identification of six types of archaeological features: settlement sites, rivers, canals, farms, grooves, and roads (hollow ways). These features used to be covered by bodies of deep water and dense zones of vegetation (reeds and papyrus).

Satellite derived bathymetry based on ICESat-2 diffuse attenuation signal without prior information

Bathymetric information is critical for environmental monitoring and maintenance of marine safety. The signal received by passive optical remote sensors contains the reflectance information from the seabed, which then forms the informational basis of bathymetry; however, passive optical bathymetry models often require partial prior information. Although spaceborne active lidar has been shown to accurately detect bathymetry within narrow range of tracks, for some small islands or coastal sites, these tracks may not accurately traverse the shallow ocean area. To this end, a satellite derived bathymetry method based on ICESat-2 diffuse attenuation signal without prior information was proposed here. The diffuse attenuation coefficients of the water column were estimated according to the ICESat-2 lidar signal of deep areas near the target shallow water area, and the parameters for the bathymetry algorithm without prior depth information were obtained. Combined with the Sentinel-2 multispectral imagery, accurate large-scale bathymetric information of Zhongye Island and Reefs, Guam, and Ngau were obtained. Bathymetric data from ICESat-2 of multiple tracks were used for verification, and the results showed that the new model performed well, as mean absolute error (MAE) for the three study areas ranged 0.35–1.52 m, and root Mean square error (RMSE) fell between 0.74 and 1.89 m. In the absence of any bathymetric information, the new method can achieve higher or similar accuracy to the more commonly employed Stumpf model.

How has the eutrophication evolved in the tributary bay of the Three Gorges Reservoir area

AbstractThe Three Gorges Reservoir on the Yangtze River is the largest water control project in the world. While exerting great benefits (i.e., flood control, hydropower generation, inland river navigation and scenic tourism), the eutrophication of the tributary bay of the Three Gorges Reservoir has become one of the main environmental problems. This paper is to study the causes of water environment evolution in the tributary bay and investigate the driving force of eutrophication succession after the Three Gorges Reservoir enters the regular operation. By considering the Meixi River on the left bank of the mainstream of the Three Gorges Reservoir area (a typical tributary), this paper developed a three-dimensional hydrodynamic, water quality and water eutrophication mathematical model for the Meixi tributary bay, calibrated with measured data about hydrological regime (water level, flow), hydrodynamic factors (velocity) and water quality (water temperature, Chl-a, TP, TN, etc.). The annual variation of Chl-a concentration in the tributary bay was simulated, and the response relationship between the variation of Chl-a concentration and water conditions of the mainstream and tributary bay (e.g., reservoir water level, reservoir bay velocity, exogenous nutrient input, water temperature stratification and other factors) was analyzed. Results show that the water storage operation of the Three Gorges Reservoir contributes to the low flow velocity maintenance (≤0.05 m/s) in the tributary bay, the backward flow of the mainstream and the sufficient nutrients carried by the tributary water; the water temperature stratification is more likely to occur in the slow detention area in the middle-upper part of the bay in spring and summer, which provides a potential driving force for algae blooms. With the continuous decline of pollution load input in the reservoir basin, the algae blooms in tributary bay was the result of the combined action of low water level operation, low flow velocity (≤0.02 m/s), a large number of non-point source loads input with rainfall and runoff (the proportion of wet year is >70%), and obvious water temperature stratification in shallow water area, and the suitable meteorological conditions are the main inducing factors. Therefore, since the ecological regulation cannot be applied to the multitudinous tributary bays, the non-point source pollution control in the tributary bay is the key to controlling factor.

Petrophysical Evaluation of the Lower Rudeis Formation in Shukheir Bay Field, Gulf of Suez, Egypt Using Open-Hole Well-Logs

The Shukheir Bay Field is located in the northern part of the Shukheir Marine Concession towards the southern part of the Gulf of Suez, about 300 km southeast of Cairo. It covers a shallow offshore water area of 5 km2 with a total area of 22.5 km2. The Rudeis sands in the Miocene sequence, which are widely distributed in the area, represent the main reservoir in the Shukheir Bay field. This study focuses on the clastic unit in the Lower Rudeis Formation usually referred to as the Lower Rudeis Sandstone. The petrophysical evaluation of this sand zone was conducted using a complete set of open-hole well-logs in three wells penetrating the formation. The lithologic composition is distinguished and identified as sand intercalated with shale, using tri and dia porosity cross plots. The shale distribution has been studied in both ways, amount and type. The amount is found to be relatively low to moderate, and the type is found to be mainly dispersed shale as indicated by the Thomas-Stieber model and the dispersed-laminated plot. The net-pay thickness also has a good value ranging from 39 m to about 42 m with high porosity (21%) and good oil saturation (76-94%). Both the vertical and lateral distributions of the petrophysical parameters are clarified, using the proper types of graphs. This research recommends drilling development wells in the central part of the study area, in addition to increase the exploration process towards the southwestern part.

Shallow Overpressure Formation in the Deep Water Area of the Qiongdongnan Basin, China

The scarcity of drilling in the deep water area of Qiongdongnan Basin restricts the cognition and prediction of overpressure. In this paper, a shallow zone of overpressure at the depth of 900–1,200 m below the sea floor in the deep water area was found by analyzing electronic logs, mud pressure (Mud pressure is a product of the height of the column of mud, density and gravity acceleration) and test pressure from drill stem testing (DST) and modular dynamic testing (MDT), and the interpretation of anomalous seismic interval velocities. The shallow overpressure is a newly observed geological phenomenon in the South China Sea for which the generation mechanisms are not well understood, despite similar observations and analyses elsewhere in the world. Two representative wells, one each located in the shallow water and the deep water areas, respectively were selected to investigate the vertical distribution of the shallow overpressure. The top of the overpressure in Well A in the shallow water area is about 2,111 m below sea floor, while the top of the overpressure in Well B in the deep water area is about 1,077 m below sea floor. A pressure coefficient (i.e., ratio of pore pressure to the normal hydrostatic pressure measured from the sea surface) profile was constructed from the shallow water area to the deep water area using the calibrated relationship between seismic interval velocities and pressure data from 30 wells. The distance between the top of the overpressure and the seabed is predicted to be between 900 and 1,200 m in the deep water area Basin. Disequilibrium compaction is the interpreted primary cause of the shallow overpressure and the results of basin modeling indicate that the shallow overpressure was generated since 5.5 Ma.

Lithological-genetic features of Starorusskaya, Vasileostrovskaya and Siverskaya formations of the Upper Vendian-Lower Cambrian Baltic-Ladoga Monocline

Research subject. Sections of the Upper Vendian-Lower Cambrian, opened at the beginning of the XXI century by wells Avloga-12R, Utkina Zavod - 1 and Thais-2 with a depth of 150-370 m, in the north and in the central part of the Leningrad region. Methods. The analysis of the structural and textural features of the rocks of the contact layers, the distribution of allotigenic (quartz, feldspar) and autigenic (pyrite, siderite, glauconite) minerals in them allowed us to supplement the characteristics of the Old Russian, Vasileostrovsky and Siverskaya formations previously isolated in these wells. The use of the structural-genetic method made it possible to clarify the volumes and boundaries of the formations, to prove the absence in the section of the Lomonosov formation, previously isolated in the well Thais-2. Results. Based on the reconstruction of sedimentation conditions and settings, the development of sedimentation processes over time, three transgressive-regressive sequences of layers - cyclothemes were established in sections. The first corresponds to the Old Russian, the second - Vasileostrovskaya, and the third - Siverskaya formation. It is shown that in the studied part of the paleobasin at the end of the Vendian-the beginning of the Cambrian, there were open shelf environments (an area of mobile shallow water with underwater shafts (zone Y), an area of relative deep water with background and storm sedimentation (zone X) and a transitional zone of patchwork sands between X and Y with a variable hydrodynamic regime. The maxima of transgressions corresponding to the development of the deepest water environments occurred in the middle of the Old Russian, Vasileostrovsky and Siversky time, and the maxima of regressions marked by shallow water deposits belong to the end of these time intervals. According to isochronous levels - maxima of transgressions and regressions, correlation of well sections was performed.

Seagrass Habitat Suitability Models using Multibeam Echosounder Data and Multiple Machine Learning Techniques

Seagrass beds are important habitats in the marine environment by providing food and shelter to dugongs and sea turtles. Protection and conservation plans require detail spatial distribution of these habitats such as habitat suitability maps. In this study, machine learning techniques were tested by using Multibeam Echo Sounder System (MBES) and ground truth datasets to produce seagrass habitat suitability models at Redang Marine Park. Five bathymetric predictors and seven backscatter predictors from MBES data were used to representing topography features and sediment types in the study area. Three machine learning algorithms; Maximum Entropy (MaxEnt), Random Forests (RF), and Support Vector Machine (SVM) were tested. The results revealed that MaxEnt and RF models achieved the highest accuracy (93% and 91%, respectively) with SVM produced the lowest (67%). Depth was identified as the most significant predictor for all three models. The contributions of backscatter predictors were more central for SVM model. High accuracy models showed that suitable habitat for seagrass is distributed around shallow water areas (<20 m) and between fringing reef habitats. The findings highlight that acoustic data and machine learning are capable to predict how seagrass beds are spatially distributed which provide important information for managing marine resources.

The relative merits of sediment transport formulas applied to the Nakdong Estuary, Korea using a coupled numerical modeling system

Three sediment transport formulas by Lund-CIRP (2012), van Rijn (1998), and Soulsby (1997) were applied for this study with field data by Yoon (2008) and several sedimentary variables of Nakdong Estuary in a coupled numerical modeling system, CMS. CMS is adopted to compare the measured depth change data and the calculated depth change data. As a result, the Lund-CIRP formula with mean grain size (0.25 mm) and multi-bottom friction coefficients based on the mean grain size distribution had higher accuracy (1.6 %) than the other formulas. The Soulsby formula has higher accuracy for multi-grain size and 0.06 of bottom friction coefficients. The van Rijn formula has high accuracy at shallow water areas such as a river. In this study, it is judged that the accuracy of the van Rijn cases was low because the water depth of the Nakdong Estuary and the nearby sea area rapidly deepens.

Голографическая обработка движущихся источников в мелком море при наличии интенсивных внутренних волн

In a shallow water area for two frequency ranges, on the basis of numerical simulation, the influence of intense internal waves that cause the interaction of sound field modes on the formation of an interferogram and a hologram of a moving source is considered. On the hologram, the spectral densities of the source field corresponding to the unperturbed and perturbed waveguides are separated. This made it possible to reconstruct the interferogram of the unperturbed field in the presence of intense internal waves. The relative error of its reconstruction is determined. The effect of a disturbance on the reconstruction of the distance and radial velocity of a source in the presence of a disturbance is estimated

Comparing measurement correction of echo sounder in shallow-water area

Comparing measurement correction of echo sounder in shallow-water area

Sedimentary phosphorus fractions in typical lacustrine wetland of Changshou Lake flowing into the Three-Gorges Reservoir.

River damming is ubiquitous which would impact the nutrient cycles of the river systems. Here an early eutrophicated reservoir (Changshou Lake) of the Three Gorges Reservoir (TGR) was selected to investigate the phosphorus (P) biogeochemical migration. Nine sediment cores were collected in the littoral nature lacustrine wetland to help to determine the phosphorus distribution and fraction along the water level. Results revealed that the concentrations of phosphorus varied from 106 to 1178mg/kg, with the highest concentration reported in the shallow water area. This was affected by the fluctuations of the water level and algae accumulation from the deep-water. In addition, it also indicated that the higher accumulation of phosphorus in the shallow water areas was predominated by HCl-P and BD-P fractions, which were potentially the main source of phosphorus in lacustrine wetlands. Hence, more attention should be paid to the autochthonous phosphorus control in the water level fluctuation area.

Multi-Platforms and Multi-Sensors Integrated Survey for the Submerged and Emerged Areas

In this paper, the state-of-the-art concerning new methodologies for surveying in coastal areas in order to obtain an efficient quantification of submerged and emerged environments is described and evaluated. This work integrates an interdisciplinary approach involving both geomatics and robotics and focuses on definition, implementation, and development of a methodology to execute integrated aerial and underwater survey campaigns in shallow water areas. A preliminary test was performed at Gorzente Lakes near Genoa (Italy), to develop and integrate different survey techniques, enabling working in a smarter way, reducing costs and increasing safety for the operators. In this context, Remote Sensing techniques were integrated with a UAV (Unmanned Aerial Vehicle) carrying an aerial optical sensor for photogrammetry and with an ASV (Autonomous Surface Vehicle) expressly addressed to work in extremely shallow water with underwater acoustic sensors (single echo sounder). The obtained continuous seamless DSM (Digital Surface Model) for the entire environment was reconstructed by the combination of different sensing systems by limiting reliance on the GNSS (Global Navigation Satellite System) support. The obtained DSM was displayed in a 3D model leading to the evaluation of the water flow volume and rendering of 3D visualization.

Reestablishment of peatland vegetation following surface leveling of decommissioned in situ oil mining infrastructures

Peatland ecosystem restoration following oil mining activities in Alberta, Canada, aims at reestablishing crucial peatland functions, such as wildlife habitat, water storage and filtration, peat accumulation, and carbon sequestration. To reinstate peatland functions, characteristic hydrological conditions are necessary to support the establishment and growth of characteristic wetland vegetation. Following in situ oil sands well pad disturbances in the Peace River and Cold Lake Oil Sands regions in Alberta, we evaluated the efficiency of peatland restoration approaches including different groundwork and revegetation techniques. Groundwork techniques included the complete removal (CR) or partial removal (PR) of the former in situ well pads' mineral fill and revegetation included the spontaneous revegetation via natural ingress of diaspores from nearby peatlands, or managed revegetation via planting of Carex aquatilis, Larix laricina, and Salix lutea. We assessed the plant species composition, biochemical and hydrological properties of all study areas, including restored peatland areas, an unrestored area, and reference areas (REF) for comparison. Ten years post‐restoration, in the restored areas the mean total plant cover was 57% with an average of 35 vascular plant and bryophyte species, while in REF 68% mean total plant cover and an average of 64 plant species were recorded. Respectively, characteristic peatland species contributed to 61 and 100% of the species composition. PR and hydrological connection to the adjacent peatland resulted in near surface water table and the highest peatland plant species diversity, while CR promoted the formation of a shallow open water area.

Water depth determines spatial and temporal phosphorus retention by controlling ecosystem transition and P-binding metal elements

Shallow lakes are more susceptible to eutrophication than deep lakes. The geochemical and biogeochemical mechanisms controlling the vulnerability to eutrophication for deep lakes and shallow lakes remain unknown. Therefore, we investigated the combined Phosphorus (P) retention mechanism with P fractions, water depth, distribution of P-binding metal elements, and macrophytes coverage in a degrading ecosystem of Erhai Lake. We concluded that different mechanisms control the P retention in deep-water areas and shallow-water areas. In shallow areas covered by macrophytes, the biogeochemical process manipulates the P retention by changing the total organic carbon (TOC), calcium (Ca) distributions and turbulence. In deep areas without macrophyte coverage, the aluminum (Al) and iron (Fe) distributions control the P retention by a physicochemical process. Manganese (Mn) was found to be a potential proxy in tracking the kinetic release and readsorb of redox-sensitive P (BD-P) in deep areas. The historical record and core sample indicate that the hydrological engineering induced water depth variation is a vital factor changing the ecosystem of Erhai Lake by forming a large area of intermediate area where macrophytes could only survive at low water level. The uplift of water level in the 1990s gradually changed the ecosystem of Erhai Lake from macrophyte-dominated to algal-macrophyte concomitant that reduced the accumulation of stable P fractions and their binding metals. Macrophytes were capable to preserve P in biomass in the macrophyte-dominated ecosystem, which released 150% and 72% of more labile organic P (NaOH25-nrP) and BD-P in the sediment after the deterioration than before, respectively. Therefore, water depth is a prerequisite to restoring the P preservation capacity of sediment and the macrophyte ecosystem. Further hydraulic engineering projects should consider the effect of water-level-variation-induced ecosystem transition.

Flood Inundation Analysis of Xun River Based on 1D and 2D Hydrodynamic Coupling Model

The Xun River is prone to flooding due to its tortuous course and low flood control standards. In this paper, the 1D and 2D hydrodynamic coupling model is used to simulate the flood situation of the Xun River in different return periods, obtain the initial inundation time, maximum inundation depth, maximum inundation area and other information of the flood, and comprehensively analyse the changes in the flood area of different water depth and different townships. The results show that with the increase of return period, the flood inundation range and inundation depth also increase, and the initial inundation time of the flood decreases; the proportion of shallow water areas of 0.05-0.5 meters decreases, and the proportion of deep water areas exceeding 3 meters increases; compared with the flood situation in different townships, Zhonglou Town is more seriously affected, and the area and population of various assets affected by the flood in Zhonglou Town are greater than that of Huangdun Town. This research provides guiding significance for the prevention and control of flood disasters in the Xun River and the rescue and disaster relief.