Lake Shoreline Research Articles

Evaluating the Current Situation of River and Lake Shoreline Planning and Utilization Using an Improved Matter-Element Extension Model

Based on the analysis of the influencing factors of the current planning and utilization of river and lake shorelines, an index system of the current planning and utilization of river and lake shorelines is constructed. Based on the triangular fuzzy number method and the improved CRITIC method, the evaluation indicators are weighted and analyzed and then integrated to obtain the combined weight. An improved matter-element extension model was constructed to evaluate the current situation of shoreline planning and utilization in typical regions. At the same time, the TOPSIS evaluation model and the cloud theory evaluation model were compared and analyzed to verify the accuracy of the model. The improved matter-element model accounts for indicator incompatibility and the uncertainty of evaluation boundaries, offering a clearer reflection of the planning and utilization status.

Changes monitoring in Hongjiannao Lake from 1987 to 2023 using Google Earth Engine and analysis of climatic and anthropogenic forces

The research aimed to quantify the lake area dynamics, evaluate the changes in distance and rate of lake shorelines quantitatively and spatially and investigate the key factors influencing the Hongjiannao Lake (HL) area shrinkage. The study used remote sensing (RS) data from Landsat TM/ETM+ and OLI images and Google Earth Engine (GEE), a cloud platform for obtaining the lake surface area and island information from 1987 to 2023. A modified normalized difference water index (MNDWI) was applied to water area extraction. Digital Shoreline Analysis System (DSAS) was employed to assess net shoreline movement (NSM) and depict the lake shoreline length and rate changes. Furthermore, the water level was derived by ASTER GDEM V2 using the waterline method and lake boundaries. Six climatic features (temperature, precipitation, potential and actual evaporation, aridity index, and actual water difference) were investigated to find the driving factors of lake area shrinkage by correlation and factor analysis. The results reveal that during 1987–2023, the HL area has undergone four separate phases: stable (1987–1997), shrinkage (1998–2015), growth (2016–2019), and reduction (2020–2023). The most substantial negative change (−7.45%) in the HL area was observed in 1998. NSM analysis demonstrates that the lake has experienced both expansion and shrinkage at various times and locations. According to Water Balance Method, the water volume of HL exhibited variations, ranging from −0.1895 to −0.009 km³. The average yearly change in lake volume, water level, and area displayed similar characteristics with high inconstancy. Correlation and factor analysis of lake area and climatic factors demonstrate that higher precipitation, low temperatures, less potential evaporation level, lower actual evaporation rates, and more minor differences in water levels are associated with an increase in lake area. In contrast, the opposite conditions lead to a reduction in lake size.

Permafrost-dissolved organic carbon and cladoceran grazing regulate bacterial abundance and community structure

The thawing of frozen soils has resulted in the release of tremendous amounts of organic carbon. Permafrost-derived dissolved organic carbon (DOC) has been demonstrated to be biolabile to microbes in aquatic ecosystems. Cladoceran grazing is another regulatory force that may affect the properties and/or characteristics of the bacterial community. However, the effects of permafrost DOC and cladoceran grazing on bacterial abundance, community composition, and diversity in aquatic ecosystems have rarely been explored. In this study, DOC was extracted from frozen soils adjacent to the shoreline of a pristine alpine lake and used to culture bacteria. The bacterial abundance decreased over time during the bioincubation experiment, whereas Daphnia feeding had no significant effect on the bacterial abundance. The genera Pedobacter, Novosphingobium, Flavobacterium and Limnohabitans had relatively high abundances after a 27-d bioincubation period. The overall decrease in bacterial diversity in the Daphnia grazing experiment was higher than that in the bacterial incubation experiment. The co-occurrence network demonstrated that terrestrial and microbial humic-like components C1 and C2 had strong interactions with Pseudolabrys, and tyrosine-like component C3 presented ­correlations with Hyphomicrobium and Vampirovibrio. Bacterial communities in the two experiments were significantly different. Sphingomonadales, Sphingobacteriales, Burkholderiales, and Actinomycetales were the primary contributors to these differences. Our study contributes significantly to a broader understanding of carbon cycling and microbial food web in lakes, particularly in high-altitude and polar lakes.

Accounting for plume rise of aircraft emissions and shoreline meteorology enhances AERMOD’s description of concentrations measured around Los Angeles airport

ABSTRACT The Aviation Environmental Design Tool (AEDT), developed by the FAA, is used to analyze the environmental impact of airport activities on air quality and noise near airports. AEDT incorporates AERMOD to estimate concentrations resulting from aircraft emissions, which possess horizontal momentum as well as buoyancy. The current version (v23132) of AERMOD incorporates plume dynamics associated with such emissions as an ALPHA option. AERMET, AERMOD’s meteorological processor does not account for the meteorology of the land-water interface that is likely to be important for airports located on the shorelines of lakes or oceans. An approach to include these effects in AERMOD was previously developed. This study examines the impact of including plume rise and shoreline effects in AERMOD by evaluating model estimates of NOX and SO2 with corresponding measurements made during the Los Angeles Airport Air Quality Source Apportionment Study (AQSAS) in the winter and summer of 2012. The performance statistics resulting from this model evaluation suggest that the inclusion of plume rise of aircraft emissions and shoreline effects on meteorological inputs is likely to improve AERMOD’s ability to estimate the impact of airport emissions on surrounding air quality. Implications: Because airport emissions, particularly those from aircraft, affect local air quality, the National Environmental Policy Act (NEPA) requires the use of dispersion models such as AERMOD to assess compliance of air quality regulations when potential expansions of airport activity are planned. The current regulatory version of AERMOD does not include aircraft-specific plume rise and shoreline-related meteorological processes, which affect the dispersion of airport emissions. The preliminary evidences presented in our previous work suggest that the incorporation of these effects will enhance AERMOD’s ability to estimate NOX and SO2 concentrations associated with airport emissions. These enhancements are beneficial not only for policy-making and regulatory compliance but also for promoting sustainable development near airports and protecting public health.

First report of microplastics in water and sediments of the alkaline Bagno dell’Acqua Lake (Pantelleria Island, southern Italy)

Microplastics are ubiquitous in aquatic ecosystems and lakes are considered important sinks for this contaminant. In this study, we assessed for the first time the occurrence and spatial distribution of microplastics in surficial waters and sediment of a small alkaline lake located in the National Park of Pantelleria Island (Central Mediterranean Sea). The island is small, scarcely populated, not industrialized and ∼70 km far from the southern European and northern African shores. Water samples were collected in triplicates in different sectors of the lake using a 10 L metal bucket, while sediment sampling was carried out at seven stations along the lake shoreline, plus one station at 3.6 m depth. Results show a homogeneous distribution of microplastic in surface waters, dominated by fibers (∼90%), with a mean concentration of 0.13 ± 0.04 MP/L, which is lower than most of the lakes worldwide. Conversely, microplastics in sediment had a higher proportion of fragments and films (50%) and their concentrations range from 0 to 540 MP/kg. The highest abundance was recorded in the western sector, where most of touristic activities concentrate, and at the 3.6 m depth station, thus suggesting that the deeper parts of the lake may retain the majority of microplastics entering the system. This study shows that even in small lakes far from major anthropic pressures, sediment may contain microplastics in striking abundances, pointing out the need to assess rural and remote lakes, at present much understudied compared to lakes in highly populated regions.

Landsat Analysis of Terraced Thermokarst Lake Variability on Alaska's Coastal Plain

ABSTRACTThermokarst lakes are abundant across the Arctic landscape. Although they are largely understood to form due to thawing permafrost and subsidence, these lakes exist in a variety of forms, shapes, and sizes. Some lakes across the Arctic exhibit shallow subaqueous terraces. The terraces have previously been shown to maintain permafrost beneath them due to the presence of bedfast ice during most of the year, whereas a talik develops beneath the deeper central pool. However, the formation of these terraces and their prevalence across the Arctic are currently unknown. In this study, we mapped the locations of thermokarst lakes and their terraces in the Alaska coastal plain using Landsat imagery. We found that terraces are larger and more abundant in sandy deposits, occupying an average of 40% of the lake area, compared to 20% of the lake area in non‐sandy lithologies. Terraces are most often found on the eastern and western lake shorelines, likely associated with regional wind directions, forming on the long sides of northwest–southeast oriented lakes. We propose a conceptual model for terrace formation in sandy deposits that describes the growth of shallow littoral shelves that protect the eastern and western shorelines from erosion while allowing lake extension in the northwest and southeast directions. Finally, given the close association between bedfast ice, talik extent, and the shallow subaqueous terraces, we suggest that mapping of these relatively stable terraces may provide insights about talik extent across the Arctic coastal region. Continued warming and changes to lake ice regimes are likely to increase talik extent, which may be easily observable by temporal analysis of terrace abundance and extent in widely available remotely sensed imagery.

The lacustrine ecosystem of the Bajo de Veliz Formation: A wet spot at the Carboniferous-Permian boundary in westernmost Gondwana

During the Carboniferous-Permian transition in the westernmost part of Gondwana, the environment became drier and more seasonal than the preceding humid estuarine and fluvial habitats of the Middle Pennsylvanian of central western Argentina. The Gzhelian-Asselian Pallero Member of the Bajo de Veliz Formation, located to the east of the Paganzo Basin, represents an ecosystem preserved in lake deposits. This unit comprises lacustrine facies, and the fossil flora and fauna contained therein represent a wet refuge developed within a regionally semi-arid context. The flora is assigned to the Gangamopteris Biozone and includes specimens of lycophytes, equisetaleans, cordaitaleans, coniferophytes, and glossopterids that grew around the lake shoreline. Winged insects, arachnids, large eurypterids, and traces of fishes comprise terrestrial and aquatic fauna. This ecosystem is considered a wet spot similar to those that characterize the global paleoclimatic shift in low paleolatitudes.

Decoding the complex fluvial-lacustrine sedimentary interactions: Insights from the Neogene Guantao Formation in the Bohai Bay Basin and Modern Poyang Lake, China

Small-scale lake level variations lead to significant landward/basinward shifts in the depositional system, thereby facilitating the widespread development of fluvial-lacustrine interaction sedimentary systems. Such systems are commonly found in low-gradient shallow-water continental down-warped lacustrine basins, which are favorable for the formation of composite reservoir-caprock assemblages. Nevertheless, our understanding of the sedimentary stratigraphy of the Neogene Guantao Formation remains limited due to the complex and variable spatial and temporal associations between fluvial and lacustrine deposits. Integrated analysis of the geomorphology and stratigraphy of the modern Poyang Lake Basin and ancient Bohai Bay Basin (BBB) allows us to develop a process-based fluvial-lacustrine interaction model of shallow-water depositional system. Three physiographic zones are identified based on seasonal lake shoreline migration during a certain geological sequence unit, namely fluvial-dominated zone (FDZ), fluvial-lacustrine interaction zone (FLIZ) and lacustrine-dominated zone (LDZ), respectively. The FDZ is always above the maximum lake shoreline without affection by lake basin water body and is characterized by channelized dendritic pattern of distributary channels with positive rhythmic cycles. The FLIZ is a dynamic interaction region between the maximum lake shoreline and the lowest lake shoreline. Reticular distributary channels, delta front and prodelta/lake deposits vertically superimpose and dominate the system that is featured by complex sandbody, stacked positive and negative rhythms and strong water body segmentation. The LDZ, away from the fluvial effect, was identified below the lowest lake shoreline exhibiting polycentric sheet water body, dominated by lacustrine mudstone interspersed with thin sheet-like sandstone. These results shed light on the spatial and temporal sedimentary heterogeneity in such dynamic fluvial-lacustrine interaction systems. The proposed fluvial-lacustrine interaction model may serve as a valuable analogue for identifying sedimentary types and predicting sandstone reservoirs in similar shallow-water settings ranging from continental down-warped lacustrine basins to cratonic basins, and fault-depression basin gentle-slope belts.

Primary to post-depositional microbial controls on the stable and clumped isotope record of shoreline sediments at Fayetteville Green Lake.

Lacustrine carbonates are a powerful archive of paleoenvironmental information but are susceptible to post-depositional alteration. Microbial metabolisms can drive such alteration by changing carbonate saturation insitu, thereby driving dissolution or precipitation. The net impact these microbial processes have on the primary δ18O, δ13C, and Δ47 values of lacustrine carbonate is not fully known. We studied the evolution of microbial community structure and the porewater and sediment geochemistry in the upper ~30 cm of sediment from two shoreline sites at Green Lake, Fayetteville, NY over 2 years of seasonal sampling. We linked seasonal and depth-based changes of porewater carbonate chemistry to microbial community composition, insitu carbon cycling (using δ13C values of carbonate, dissolved inorganic carbon (DIC), and organic matter), and dominant allochems and facies. We interpret that microbial processes are a dominant control on carbon cycling within the sediment, affecting porewater DIC, aqueous carbon chemistry, and carbonate carbon and clumped isotope geochemistry. Across all seasons and sites, microbial organic matter remineralization lowers the δ13C of the porewater DIC. Elevated carbonate saturation states in the sediment porewaters (Ω > 3) were attributed to microbes from groups capable of sulfate reduction, which were abundant in the sediment below 5 cm depth. The nearshore carbonate sediments at Green Lake are mainly composed of microbialite intraclasts/oncoids, charophytes, larger calcite crystals, and authigenic micrite-each with a different origin. Authigenic micrite is interpreted to have precipitated insitu from the supersaturated porewaters from microbial metabolism. The stable carbon isotope values (δ13Ccarb) and clumped isotope values (Δ47) of bulk carbonate sediments from the same depth horizons and site varied depending on both the sampling season and the specific location within a site, indicating localized (μm to mm) controls on carbon and clumped isotope values. Our results suggest that biological processes are a dominant control on carbon chemistry within the sedimentary subsurface of the shorelines of Green Lake, from actively forming microbialites to pore space organic matter remineralization and micrite authigenesis. A combination of biological activity, hydrologic balance, and allochem composition of the sediments set the stable carbon, oxygen, and clumped isotope signals preserved by the Green Lake carbonate sediments.

Middle to Late Holocene lake level variations recorded by shoreline tufa of Longmu Co Lake, northwestern Tibet Plateau

Tufa deposits have significant potential for reconstructing past lake-level fluctuations. Here, we conducted U-Th dating of tufa deposits exposed along the shoreline of Longmu Co Lake in the northwestern Tibetan Plateau to reconstruct its water level history during the middle-late Holocene. Our data demonstrate that Longmu Co Lake reached its highest level (61 m above the present level) at around 7.4 ka in response to the strengthened Indian Summer Monsoon and increased glacial meltwater; its lake level subsequently decreased due to solar insolation-induced decline in summer monsoon and glacial meltwater. Moreover, we find that the lake level experienced an abrupt decline at ~2.2 ka with a maximum amplitude of 13 m, probably owing to the rapid cooling of the local climate. The δ18O and δ13C of Longmu Co tufa also show a covariance trend, which supports the regional climate change reflected by the lake level fluctuation of Longmu Co. Additionally, we observed an inverse correlation between initial δ234U content in tufa and lake level variation, suggesting that initial calcium δ234U can serve as a proxy for reconstructing environmental changes. Our study therefore implies that lake tufa as a reliable archive for accurately reconstructing lake level changes.

Demonstration of Multi-source Remote Sensing Fusion Technology to Identify Ancient Lake Shorelines——Qarhan Salt Lake as an Example

Demonstration of Multi-source Remote Sensing Fusion Technology to Identify Ancient Lake Shorelines——Qarhan Salt Lake as an Example

Probing sediment burial age, provenance and geomorphic processes in dryland dunes and lake shorelines using portable luminescence data

Luminescence signals from portable optically-stimulated luminescence readers (POSL or port-OSL) can provide expedient insights into sample relative age, and under certain conditions can be simplistically calibrated against existing luminescence chronologies to provide first-order estimates of burial age. This is most straightforward in simple sedimentary systems where samples share a common provenance and geomorphic process history. The spatially extensive southern African dune and palaeolake shoreline luminescence database, for which hundreds of non-light exposed bulk sediments are available, offers a valuable test case to examine the conditions under which POSL-bulk sediment calibration approaches are feasible. To do this we combine measurements of inherent luminescence sensitivity of bulk sediment (BSS) with analysis of sedimentary composition (petrology and presence of calcium carbonate) and texture. We show that BSS, along with POSL IRSL:BSL ratios and petrological data, account for region-to-region variations, whilst internal variability (scatter) within the lake shorelines dataset relates to variations in BSS and sediment texture. At the scale of southern African subcontinent drylands, we see that provenance and geomorphological process history influence sample mineralogical composition and POSL signal characteristic, including BSS.

Identification of the subaerial unconformity, genesis, and distribution in Lower Triassic Baikouquan Formation, Mahu Sag, Junggar Basin, Western China

The genesis of unconformities involves multiple influences on basin formation and evolution, which affects the favorable reservoir and hydrocarbon distribution. Within the Early Triassic Baikouquan Formation in the Mahu Sag of the Junggar Basin, we identified subaerial unconformities (SU), namely SU1 and SU2. SU1 is characterized by regional, irregular valleys, whereas SU2 displays extensive lateral extent with comparatively lower relief. These distinctions stem from detailed analyses involving cores, well data, seismic profiles, and spatial distributions, enriching our understanding of SUs in the Junggar Basin. Key findings from our study include: (1) SU occurrences within the Baikouquan Formation span the falling-stage systems tract (FSST) and expanding system tract (EST), corresponding to relative lake level changes. SU1 emerges during descending lake levels, whereas SU2 develops during rising levels. (2) The extensive uplift of the Junggar Basin's perimeter, driven by the late Hercynian movement, heightened topographic gradient shapes a steeper lake shoreline profile, fostering SU development. Arid paleoclimatic conditions during the Permian-Triassic interval accelerate SU formation in the FSST. (3) SU typically comprises regional compound scour surfaces (RCS) and river intermittent exposure surfaces (IES). Continuous winnowing at RCS led to relatively high primary porosities, IES can develop better secondary porosity with superposed freshwater leaching. The investigation into the subaerial unconformity in the study area holds broader implications for comprehending depositional processes, reservoir distribution, and petroleum prospects, both locally and within a global lake basin context.

Influence of heavy Canadian crude oil on pristine freshwater boreal lake ecosystems in an experimental oil spill.

The overall impact of a crude oil spill into a pristine freshwater environment in Canada is largely unknown. To evaluate the impact on the native microbial community, a large-scale in situ model experimental spill was conducted to assess the potential role of the natural community to attenuate hydrocarbons. A small volume of conventional heavy crude oil (CHV) was introduced within contained mesocosm enclosures deployed on the shoreline of a freshwater lake. The oil was left to interact with the shoreline for 72h and then free-floating oil was recovered using common oil spill response methods (i.e. freshwater flushing and capture on oleophilic absorptive media). Residual polycyclic aromatic hydrocarbon (PAH) concentrations returned to near preoiling concentrations within 2 months, while the microbial community composition across the water, soil, and sediment matrices of the enclosed oligotrophic freshwater ecosystems did not shift significantly over this period. Metagenomic analysis revealed key polycyclic aromatic and alkane degradation mechanisms also did not change in their relative abundance over the monitoring period. These trends suggest that for small spills (<2l of oil per 15 m2 of surface freshwater), physical oil recovery reduces polycyclic aromatic hydrocarbon concentrations to levels tolerated by the native microbial community. Additionally, the native microbial community present in the monitored pristine freshwater ecosystem possesses the appropriate hydrocarbon degradation mechanisms without prior challenge by hydrocarbon substrates. This study corroborated trends found previously (Kharey et al. 2024) toward freshwater hydrocarbon degradation in an environmentally relevant scale and conditions on the tolerance of residual hydrocarbons in situ.

渭河干流甘肃段河岸线空间变化数据集（2008、2015、2022年）

As the largest tributary of the Yellow River, the Weihe River has an important influence on the Yellow River in terms of both its flow and sediment load. Carrying out spatial and temporal evolution monitoring of the river shorelines is an important basis for grasping the hydrological changes of the river in the basin. In this study, we used the high-frequency and resource satellite image data of the Gansu section of the Weihe River in 2008, 2015 and 2022 as the base map, and extracted the river shorelines of the Gansu section of the Weihe River through the processing of image ortho-correction, alignment, fusion, mosaicing and cropping; combining with the image characteristics of the image, we adopted the method of interactive deciphering, including the Weihe River management range line, the Weihe River waterfront boundary line, and the Weihe River outer edge boundary line. Additionally, high-precision UAV aerial image data were utilized, integrating typical areas and important markers on the image base map data to ensure the reliability of river shoreline extraction. This dataset can provide data support for studying the hydrological dynamic monitoring and driving mechanisms of the Weihe River main stream. Furthermore, it can serve as basis for making informed decisions regarding the protection of river and lake shorelines and the ecological management of the river.

Possible role of anthropogenic climate change in the record-breaking 2020 Lake Victoria levels and floods

Abstract. Heavy rainfall in eastern Africa between late 2019 and mid 2020 caused devastating floods and landslides throughout the region. These rains drove the levels of Lake Victoria to a record-breaking maximum in the second half of May 2020. The combination of high lake levels, consequent shoreline flooding, and flooding of tributary rivers caused hundreds of casualties and damage to housing, agriculture, and infrastructure in the riparian countries of Uganda, Kenya, and Tanzania. Media and government reports linked the heavy precipitation and floods to anthropogenic climate change, but a formal scientific attribution study has not been carried out so far. In this study, we characterize the spatial extent and impacts of the floods in the Lake Victoria basin and then investigate to what extent human-induced climate change influenced the probability and magnitude of the record-breaking lake levels and associated flooding by applying a multi-model extreme event attribution methodology. Using remote-sensing-based flood mapping tools, we find that more than 29 000 people living within a 50 km radius of the lake shorelines were affected by floods between April and July 2020. Precipitation in the basin was the highest recorded in at least 3 decades, causing lake levels to rise by 1.21 m between late 2019 and mid 2020. The flood, defined as a 6-month rise in lake levels as extreme as that observed in the lead-up to May 2020, is estimated to be a 63-year event in the current climate. Based on observations and climate model simulations, the best estimate is that the event has become more likely by a factor of 1.8 in the current climate compared to a pre-industrial climate and that in the absence of anthropogenic climate change an event with the same return period would have led lake levels to rise by 7 cm less than observed. Nonetheless, uncertainties in the attribution statement are relatively large due to large natural variability and include the possibility of no observed attributable change in the probability of the event (probability ratio, 95 % confidence interval 0.8–15.8) or in the magnitude of lake level rise during an event with the same return period (magnitude change, 95 % confidence interval 0–14 cm). In addition to anthropogenic climate change, other possible drivers of the floods and their impacts include human land and water management, the exposure and vulnerability of settlements and economic activities located in flood-prone areas, and modes of climate variability that modulate seasonal precipitation. The attribution statement could be strengthened by using a larger number of climate model simulations, as well as by quantitatively accounting for non-meteorological drivers of the flood and potential unforced modes of climate variability. By disentangling the role of anthropogenic climate change and natural variability in the high-impact 2020 floods in the Lake Victoria basin, this paper contributes to a better understanding of changing hydrometeorological extremes in eastern Africa and the African Great Lakes region.

Assessing lake shoreline change and prediction for 2030 by physical drivers: A Case Study from Lake Batur, Batur UNESCO Global Geopark, Bali

Over ten years, the water level of Lake Batur has increased. Agriculture area and settlements around Lake Batur are threatened by rising water level. This study aims to analyze the shoreline change of Lake Batur, located in the Batur UNESCO Global Geopark (BUGG), during the period of 2007 – 2018 and design a prediction for 2030. Understanding the shoreline change is very important for lake management and planning. Shoreline changes were analyzed in Geographic Information System (GIS) application. The data were obtained based on Remote Sensing (RS) data, Landsat ETM+ imagery on September 24, 2007, and Landsat OLI imagery on October 24th, 2018. Predictions of lake shoreline in 2030 result from modelling by integrating ASTER-GDEM V2 data, lake water level data for 2007–2018, annual average rainfall data for 2007–2018, and bathymetry data for 2013 and 2015. The results of the satellite imagery analysis show that there has been a change in the length of the shoreline, which has increased from 20.47 km in 2007 to 21.28 km (3.96%) in 2018. The lake surface area changed from 15.34 km2 in 2007 to 16.16 km2 in 2018 (5.35%). The prediction of lake shoreline changes in 2030 showed that Lake Batur will increase to 26.90 km (26.41%), and lake surface area is predicted to increase by 17.67 km2 (9.34%) from 2018. This is because of the morphological change of Lake Bottom.

Selected methods for determining inconclusively identifiable shorelines of watercourses and lakes

Abstract The determination of a lake or natural watercourse shoreline is the subject of various administrative proceedings relating to, among others, the engineering of riverbeds, construction of hydro-technical facilities, remediation work, land division, or delimitation of parcels. The provisions of law, while laying out the rules for determining shorelines, do not explicitly specify the measurement method to follow. All the more so, as many shores of lakes and watercourses are among terrain details that are difficult to measure due to their varied accessibility, which depends on the terrain, vegetation, and water conditions. The purpose of this paper is to compare selected methods for determining the shoreline of watercourses and lakes in terms of their applicability under different environmental conditions under current legislation. This study comprises an assessment of the suitability of the applied methods of shoreline measurement under varying field conditions and their applicability in surveying work on shoreline determination. Surveys were conducted on 3 reservoirs and one watercourse using geodetic, photogrammetric, and remote sensing techniques, and the suitability of the various methods was evaluated with respect to the field conditions of the measurements.

Sedimentary characteristics, formation conditions, and distribution mechanisms of beach bar sand bodies of Chang 82 submember, southwest Ordos Basin

AbstractBeach bar sand bodies are a relatively new type of reservoir in oil exploration where they can be found in the proximity of the source rock. In this study, the genetic type of sand bodies in the Upper Triassic Yanchang Formation in the southwest Ordos Basin is systematically studied through the observation of outcrops, core description, microscopic inspection of thin sections, along with petrophysical properties, mineralogy, and geochemical analysis of trace elements. The results showed that a new sedimentary type of beach bar sand bodies are developed in the Chang 82 submember of the Yanchang Formation, that are generally characterized with a flat bottom and convex top, where the contact interface between the bottom of the single sand body and mudstone is flat, and the bottom lacks erosion and filling structure. Moreover, a variety of wave‐induced sedimentary structures are developed, showing a reverse sedimentary sequence from fine to coarse grains. The structural and compositional maturity of the beach bar sand bodies are higher than that of the river channel sand body. Moreover, reservoir pore type is mainly comprised of intergranular pores, and the porosity and permeability of the samples retrieved from the sand body are much higher than that of the river channel sand body. Finally, the main controlling factors of the formation and preservation of beach bar sands are found to be the lake basin bottom topography, the base level cycle, and the stable paleo‐lake shoreline. During the Chang 82 submember depositional period, a large area where the beach bar sand bodies were deposited parallel to the lake shoreline in the southwest of the basin was created. Such depositional environments had suitable conditions to host large‐scale oil‐bearing reservoirs, as major exploration and development targets in the Ordos Basin in the future.

Macronutrients and their ratios in different plant species growing in solonchaks of Western Transbaikalia

The macroelement composition and ratios of macroelements in dominant and co-dominant plants growing on lakeside solonchaks of Western Transbaikalia: from salt-sandy strips on dried shoals with pioneer groupings, side slopes to plains with cheieves, irises and leymus communities were studied for the first time. General regularities characterizing their macroelement composition were established for annual halophytes of salt-sand strips of the Beloe Lake shoreline. It has been revealed that pioneer perennials are formed on the mortmass of annuals. Mortmass of different duration of formation was characterized by high silicic content and concentrations of S, Fe, and Mg with a minimal amount of K, and the K : Na ratio was 0.03–0.04. Biological productivity of lakeside saltmarsh communities was determined to be normal and elevated, 1490–3080 g dry mass/m2/year. Species differed significantly in the macroelement composition depending on the conditions of growing in the coastal zone of brackish lakes. Common for the chemical composition of plants was a relatively high content of nitrogen and ash. It was found that by the total concentration of K, Ca, Mg, Na, Si in the dry matter, annuals of the Chenopodiaceae family dominated due to the high amount of sodium. In spite of non-compliance with the norms of the ratios of most macronutrients in the dry matter of plants, especially by K : (Ca + Mg) and K : Na, all species are used as fodder in different periods of the year.