Estuary Basin Research Articles

Characterizing spatio-temporal variations of dimethyl sulfide in the Yellow and East China Sea based on BP neural network

Dimethyl sulfide (DMS), an organic volatile sulfide produced from Dimethylsulfoniopropionate (DMSP), exerts a significant impact on the global climate change. Utilizing published literature data spanning from 2005 to 2020, a BP neural network (BPNN) model of the surface seawater DMS in the Yellow and East China Sea (YECS) was developed to elucidate the influence of various marine factors on the DMS cycle. Results indicated that the six parameters inputted BPNN model, that include the time (month), latitude and longitude, sea-surface chlorophyll a (Chl-a), sea-surface temperature (SST), and sea-surface salinity (SSS), yielded the optimized simulation results (R2 = 0.71). The optimized estimation of surface seawater DMS in the YECS were proved to be closely aligned with the observed data across all seasons, which demonstrated the model’s robust applicability. DMS concentration in surface seawater were found to be affected by multiple factors such as Chl-a and SST. Comparative analysis of the three environmental parameters revealed that Chl-a exhibited the most significant correlation with surface seawater DMS concentration in the YECS (R2 = 0.20). This underscores the pivotal role of chlorophyll in phytoplankton photosynthesis and DMS production, emphasizing its importance as a non-negligible factor in the study of DMS and its sulfur derivatives. Furthermore, surface seawater DMS concentration in the YECS exhibited positive correlations with Chl-a and SST, while displaying a negative correlation with SSS. The DMS concentration in the YECS show substantial seasonal variations, with the maximum value (5.69 nmol/L) in summer followed in decreasing order by spring (3.96 nmol/L), autumn (3.18 nmol/L), and winter (1.60 nmol/L). In the YECS, there was a gradual decrease of DMS concentration from the nearshore to the offshore, especially with the highest DMS concentration concentrated in the Yangtze River Estuary Basin and the south-central coastal part off the Zhejiang Province. Apart from being largely composed by the release of large amounts of nutrients from anthropogenic activities and changes in ocean temperature, the spatial and temporal variability of DMS may be driven by additional physicochemical parameters.

안악 3호분 벽화의 중원 색채와 그 의의

The main content of the mural painting of Anak Tomb No. 3, a tomb which belongs to the emergent stage of Goguryeo mural tombs, is the life of the tomb owner in his life. It is the same with the mural tombs of China from the Eastern-Han Dynasty. Anak Tomb No. 3 is quite similar to the mural tombs of central China and Liaoyang in terms of the structure of the tomb, as well as the composition and content of the mural painting. Various prestige goods such as a type of cart (通幰車), drapes and a tent (帷帳), a folding screen and flat bench (屛榻), a type of pole (節), a type of folding fan (麈尾扇) depicted on the mural painting of Anak Tomb No.3 represent the official rank, written in black ink on the mural painting of this tomb’s owner, and these contents are the same as those of the mural tombs of central China which are of the same level. This presence of objects originating from central China found on the mural painting of Anak Tomb No.3 and Deokheungri tomb indicates that the Daedong River Estuary basin (which includes the Pyongyang area) maintained a different social and cultural aspect from the Jian area, until the Goguryeo capital was relocated from Jian to Pyongyang in 427. There is a view that Dong Su was not the owner of the tomb, but a gate guard (門吏) written as “Jang Ha Dok” (帳下督) on the wall of the entrance of the western chamber. “Jang Ha Dok” is a subordinate official belonging to the first to third rank of the Wei-Jin Period. According to an ink handwriting record, Dong Su’s rank corresponds to the second to third official rank of the Wei-Jin Period. Therefore, Dong Su cannot be regarded as “Jang Ha Dok”. A type of pole called “jul” (節) on the mural painting reflects the office of “Sa Ji Jul” (使持節) written in black ink. In addition, the oxcart with the tomb owner is a type of cart called Tong Hun Gu (通幰車), which the second to third official rank rode. Therefore, it is most reasonable to regard the owner of Anak Tomb No. 3 as Dong Su, as is written in black ink.

River Ecosystem Health Assessment in Rapid Urbanization Regions (Shenzhen, China) under the Guidance of Bioremediation Objectives

As a coastal city with rapid urbanization and high-intensity human activities, Shenzhen, China has carried out a series of comprehensive treatments for water pollution control and ecological restoration in recent years. However, the restoration effect is mainly reflected in the improvement of water quality and riparian landscape, and there is still a big gap in reaching the river’s ecological restoration goals. Therefore, it is necessary to make a full investigation and evaluation of river aquatic systems that focuses on the restoration of aquatic communities and ecosystem health. We surveyed forty-seven sampling sites in nine basins to investigate water quality and aquatic organisms (algae and macroinvertebrates) during the low-water period in 2019. Under the guidance of the EU Water Framework Directive (WFD), the urban river ecosystem health assessment system, with a total of twenty indicators from six criteria layers, was established. We addressed the bioremediation objectives in this system and aquatic organism indicators as high-weight characteristic indicators. The results showed that the degradation of the river ecosystem in Shenzhen is serious, which is mainly reflected in the simple structure of the aquatic biological community and the low biodiversity. Only one “healthy” sample site, accounting for 2% of the total sampling sites; six sites of “sub-health” level, accounting for 13%; twenty-four “poor” sample points, accounting for 51%; sixteen “extremely poor” sample points, accounting for 34%. From the perspective of spatial distribution, the river ecological status of Daya Bay Basin and Dapeng Bay Basin is good, which is at the level of “health” to “sub-health”; the Guanlan River Basin, Maozhou River Basin, Shenzhen River Basin, Shenzhen Bay Basin, Pingshan River Basin, and most of the Longgang River Basin are of “poor to extremely poor” grade; the Pearl Estuary basin is of “extremely poor” grade. This assessment system can be used as an effective tool to monitor the ecological health status, especially the enhancement of biodiversity and ecosystem function of rivers. Moreover, it could provide important decision-making guidance for river management affected by high-intensity human activities.

Geoarchaeology and Coastal Morphodynamics of Harbor Key (8MA15): Indigenous Persistence at a Partially Inundated Native Shell Mound Complex in Tampa Bay, Florida

AbstractApplying a coastal-geoarchaeological approach, we synthesize stratigraphic, sedimentological, mollusk-zooarchaeological, and radiometric datasets from recent excavations and sediment coring at Harbor Key (8MA15)—a shell-terraformed Native mound complex within Tampa Bay, on the central peninsular Gulf Coast of Florida. We significantly revise the chronological understanding of the site and place it among the relatively few early civic-ceremonial centers in the region. Analyses of submound contexts revealed that the early first millennium mound center was constructed atop a platform of sand and ex situ cultural shell deposits that were reworked during ancient storm landfalls around 2000 BP. We situate Harbor Key within a seascape-scale stratigraphic and paleoenvironmental framework and show that the shellworks comprise an artificial barrier protecting the leeward estuary basin (and productive inshore wetlands) from high-energy conditions of the open bay and swells from the Gulf of Mexico. The sedimentary and archaeological records attest to the long-term history of morphodynamic interaction between coastal processes and Indigenous shell terraforming in the region and suggest that early first millennium mound building in Tampa Bay was tied to the recognition and reuse of antecedent shellworks and the persistent management of encompassing cultural seascapes.

ORGANIZATIONAL AND ECONOMIC PRINCIPLES OF CONSERVATION AND ENSURING SUSTAINABLE DEVELOPMENT OF THE KUIALNYK ESTUARY

ORGANIZATIONAL AND ECONOMIC PRINCIPLES OF CONSERVATION AND ENSURING SUSTAINABLE DEVELOPMENT OF THE KUIALNYK ESTUARY

Ichthyofaunas of nearshore, shallow waters of normally-closed estuaries are highly depauperate and influenced markedly by salinity and oxygen concentration

This study determined the ichthyofaunal characteristics of the nearshore, shallow waters of three normally-closed estuaries (Stokes, Culham and Hamersley inlets) on the south coast of Western Australia over three years, during which each system remained closed to the ocean through the recent formation of a sand bar at its mouth. The ichthyofauna in each estuary was depauperate (6 or 7 species) and overwhelmingly dominated by small euryhaline atherinid and gobiid species and a larger sparid, which each complete their life cycle within their natal estuary. The atherinid Atherinosoma elongatum contributed between 74.5 and 94.5% to the ∼168,000 fish collected from these three estuaries. In contrast, marine species were represented solely by six Aldrichetta forsteri (Mugilidae), likely derived from overwash of the bar. The degree to which salinity increased and oxygen declined during the three years of closure varied markedly among the three estuaries. Among estuary basins, the number of species and density of fishes declined most rapidly in Culham Inlet, where mean salinity rose sharply from 52 to 293 and oxygen concentration fell precipitously to 0.6 mg L−1, with only A. elongatum present in salinities up to 147 and oxygen concentrations down to 2.4 mg L−1. In contrast, number of species and density of fishes remained relatively constant in the basin of Stokes Inlet, where salinity rose to only 64 and oxygen concentration declined to only 5.5 mg L−1, with ichthyofaunal and environmental changes in the basin of Hamersley Inlet intermediate between those in Culham and Stokes. While species were variably partitioned between the basin and river, certain species, when subjected to extreme salinities in the basin, moved into the less saline riverine reaches of the estuary, with the isolated pools that form upstream in estuaries during very dry periods providing refugia. In estuaries on the extensive south-western Australian coastline, the number of fish species, and particularly the number and abundance of marine species, undergo an overall progressive decline down the lower west coast and eastwards along the southern coast where they eventually fall to minimal levels. This reflects the overall trend for estuaries to change from permanently-open to the ocean to intermittently-open, to seasonally-open and finally normally-closed.

Dissolved Oxygen Prediction Model for the Yangtze River Estuary Basin Using IPSO-LSSVM

Water ecology has always been key to environmental protection, and the combination of human activities and natural factors has caused eutrophication in the Yangtze estuary and adjacent waters. Among them, dissolved oxygen (DO) concentration is the key indicator to judge the quality of water. Firstly, using principal component analysis (PCA) to determine the number of parameters affecting dissolved oxygen concentration, the least squares support vector machine (LSSVM) prediction model with improved particle swarm optimization (IPSO) is proposed to be applied to the dissolved oxygen prediction in Shanghai’s Yangtze River basin through the data-driven modeling approach and the regression prediction capability of the neural network. Eight parameters of water temperature (WT), pH, potassium permanganate (KMnO4), ammonia nitrogen (NH4+-N), total phosphorus (TP), total nitrogen (TN), conductivity (Cond), and nephelometric turbidity unit (NTU) are selected as model inputs in the published public data, and the output is the dissolved oxygen concentration. The optimal combination of model parameters is found according to the IPSO algorithm, which effectively overcomes the parameter selection problem of regular support vector machines (SVM). The mean absolute error (MAE), root mean square error (RMSE), mean absolute percentage error (MAPE), and correlation coefficients of the evaluation indexes of this model (R2) are 0.1702, 0.2221, 0.0267, and 0.9751, respectively. Compared with other similar data driven models, this model has improved model accuracy and stability in predicting DO concentrations in the estuary, and thus it provides technical support for assessing and monitoring offshore water quality.

Habitat compression of an estuarine mytilid following half a century of streamflow decline

The distribution of species throughout estuaries is often regulated by salinity gradients, among other key environmental drivers. In many temperate estuaries, however, declining streamflow has led to increased marinization and thus potential habitat compression of some species. Since the mid-1970s, estuaries in south-western Australia have experienced among the greatest decline in streamflow in Australia due to a drying and warming climate. The resultant habitat modification would be particularly unfavourable to sessile fauna, such as mytilid mussels, which are unable to relocate due to their attachment to substrate via byssal threads. This study compared the settlement (and adult survival) of Black Pygmy Mussel Xenostrobus securis in the Swan-Canning Estuary with that described in this system sixty years earlier, over which time freshwater discharge declined by >50%. During the 1960s, settlement of X. securis occurred throughout much of the estuary, beginning in the estuary basin in November and in the upper Swan River in February/March as winter freshwater flow subsided and salinities increased. In contrast, in the current study (2019/2020), X. securis settlement was largely restricted to the upper zones of the estuary. Settlement of X. securis larvae also began much earlier, occurring in the upper Swan River in October, compared with February/March during the 1960s. This is consistent with the salinity tolerances of larval X. securis and declining streamflow, leading to increased marinization of the estuary basin and earlier encroachment of the salt-wedge upstream. In addition, the increased frequency of summer streamflow events in recent decades makes X. securis populations even more vulnerable to substantial mortalities caused by rapid dilution of salinity at warmer temperatures. Thus, the combination of habitat compression, from declining streamflow and increased occurrence of extreme summer rainfall events are likely to pose substantial problems for the survival of X. securis populations in this region into the future. The results of this study further our knowledge on the potential impacts of environmental change on sessile fauna and is of interest to environmental managers.

Evolution of the hydrocarbon migration system of the lower enping formation in the pearl river estuary basin

The Enping Formation of the Paleogene System in the Lufeng south area of the Pearl River Estuary Basin has good potential for hydrocarbon exploration. It is characterized by a vertically large distribution of a crude oil type and a widely horizontal distribution of similar crude oil. With the complex characteristics of hydrocarbon distribution and migration, studying the evolution mode of this migration system on a dynamic scale is necessary. In this study, the key accumulation period was determined using existing logging, seismic, and microscopic data combined with fluid inclusion and burial history. Then, the system's migration path and the direction of migration in the key accumulation period were analyzed, and the migration system and evolution model in the study area were established. The results show two stages of accumulation in the southern Lufeng area: 19–8 Ma and 8–0 Ma. In the first stage, the reservoir mainly followed the transport of a far-source fault–sand–ridge coupling system and the traps on the migration path were favorable for hydrocarbon accumulation. In the second accumulation period, traps that developed near the oil-source faults were favorable for hydrocarbon accumulation. The favorable traps in the first accumulation period were distributed in the whole area. The traps in the southwest wells B921 and C1211 were larger than the first stage, whereas the favorable traps in the northeast and central parts were mainly distributed in B211D and its adjacent well area, with smaller and scattered traps. Favorable traps in the second accumulation period were mainly distributed in the eastern and central regions, around wells B211D and B161, whereas the traps in the southwest were not conducive to hydrocarbon accumulation due to the lack of effective transport system connection. The results of this study have a certain guiding significance for practical exploration.

Distribution and Genesis Analysis of Overpressure in X Area of Pearl River Estuary Basin

Distribution and Genesis Analysis of Overpressure in X Area of Pearl River Estuary Basin

HISTORY OF CREATION AND CURRENT STATE OF THE OVOSELSKY-ROZHKOVA DAM (KUYALNITSKY LIMAN)

Problems Statement and Purpose. The Kuyalnitskiy estuary is located within the northwestern estuary coastal region, in the interfluve of the Southern Bug and Dniester rivers. This is a closed estuary, which is separated from the sea by an embankment and has no direct connection with it. Nature management in the estuary basin during the 19th‑20th centuries was carried out disregarding the natural territorial regularities and led to a critical condition of the geosystem of the reservoir. Hydrotechnical engineering on the banks and waters of the Kuyalnitsky Estuary was aimed at regulating the hydrological regime in order to create favorable conditions for salt precipitation. One of these structures is an unexplored Novoselsky-Rozhkov dam. Data & Methods Measurements were carried out using geodetic rail 3 m long, being on the rubber boat. Determination of depths and coordinates was carried out after the boat stopped at the measurement point. Аlong with measurements were determined the depths above the flooded crest of the hydrotechnical structure. The surface of the dam was explored by walking routes. The position of the boat and points on the dam was determined by Garmin GPS72H navigator. Depths were determined with an accuracy of 0.01 m. The studies were carried out under conditions of complete calm; during measurements at a temporary water measuring post no level fluctuations were recorded. Results. One of the hydrotechnical objects that exist in the water area of the estuary is the Novoselsky -Rozhkov dam. Dam was built in 1858–1859. to transform the Kuyalnitsky estuary into salt-forming self-sedimentary lake. Initial parameters of the dam: length – 2929 m, width along the top – 6.4 m, width in the lower part – 17.1 m. The height of the structure did not exceed 1 m above the water level due to constant subsidence on soft soils in the estuary. During the 165 years of its existence, the above-water part of the dam was destroyed by floods. The parameters of the underwater part and the axis of the structure remained close to the initial ones: length – 2900 m, average top width –14.2 m. The modern surface profile of the dam has a concave shape and is the same as the bottom profile. The dam affects the natural system of the Kuyalnitsky estuary as an artificial relief form: it causes the accumulation of material at the bottom and near the shore in the southern corners of the structure; water temperature rise in coastal shallow waters and above the surface of the dam by 2–3 0 С was noted in comparison with the water masses of the nearby water area.

Evolution of the Hydrocarbon Migration System of the Lower Enping Group in the Pearl River Estuary Basin

Evolution of the Hydrocarbon Migration System of the Lower Enping Group in the Pearl River Estuary Basin

Deep-Water Oil and Gas Exploration in Northern South China Sea: Progress and Outlook

Strengthening exploration and development of oil and gas is crucial for mitigating China’s reliance on oil and gas supply from foreign countries and ensuring national energy security. Since the 11th Five-Year period, fundamental research on the deep-water area of the northern South China Sea has been strengthened, along with the acceleration of technological innovation and increase in exploration investment. As a result, a series of major exploration discoveries were found. This paper presents five major learnings regarding the theories of exploration geology and two achievements in the innovation of exploration technology. It also discusses the new challenges and coping strategies for oil and gas exploration in deep-water areas, and prospects the exploration potentials of three major exploration fields—medium-deep layers, buried hills, and lithologic traps—in the deep-water area of the northern South China Sea. Our research shows that the detachment of the continental margin in the deep-water area of northern South China Sea controls the formation of large sags in the Pearl River Estuary Basin and the Qiongdongnan Basin. Three sets of large-scale source rocks were developed from lacustrine, terrestrial-marine transitional, and marine sedimentary facies. High yet variable subsurface temperature controls the rapid hydrocarbon generation from the source rocks in the sags. In addition, three different hydrocarbon accumulation modes were established: accumulation mode of large axial canyon channel in the deep-water area of the Qiongdongnan Basin, late natural gas accumulation mode of deep-water fan in the deep-water area of Baiyun Sag, and differential hydrocarbon accumulation mode jointly controlled by fault and ridge. Meanwhile, the broadband seismic acquisition and processing technology for three-dimensional source triggering and plow-like cable receiving was independently developed. Guided by several geological theories and innovative technologies, a series of large- and medium-sized gas fields represented by “Deep Sea No. 1” (LS 17-2) were discovered, which are of great significance to ensuring the energy supply of the Guangdong-Hong Kong-Macao Greater Bay Area, facilitating the green development of energy in the Hainan Free Trade Zone (Port), and promoting the increase of oil and gas reserves and production in China.

Long-Term Assessment of Surface Water Quality in a Highly Managed Estuary Basin.

Anthropogenic developments in coastal watersheds cause significant ecological changes to estuaries. Since estuaries respond to inputs on relatively long time scales, robust analyses of long-term data should be employed to account for seasonality, internal cycling, and climatological cycles. This study characterizes the water quality of a highly managed coastal basin, the St. Lucie Estuary Basin, FL, USA, from 1999 to 2019 to detect spatiotemporal differences in the estuary’s water quality and its tributaries. The estuary is artificially connected to Lake Okeechobee, so it receives fresh water from an external basin. Monthly water samples collected from November 1999 to October 2019 were assessed using principal component analysis, correlation analysis, and the Seasonal Kendall trend test. Nitrogen, phosphorus, color, total suspended solids, and turbidity concentrations varied seasonally and spatially. Inflows from Lake Okeechobee were characterized by high turbidity, while higher phosphorus concentrations characterized inflows from tributaries within the basin. Differences among tributaries within the basin may be attributed to flow regimes (e.g., significant releases vs. steady flow) and land use (e.g., pasture vs. row crops). Decreasing trends for orthophosphate, total phosphorus, and color and increasing trends for dissolved oxygen were found over the long term. Decreases in nutrient concentrations over time could be due to local mitigation efforts. Understanding the differences in water quality between the tributaries of the St. Lucie Estuary is essential for the overall water quality management of the estuary.

Variability in infragravity wave processes during estuary artificial entrance openings

ABSTRACTIntermittently open/closed estuaries (IOCE) are wave‐dominated estuaries with entrances that temporarily close to the ocean. Wave–current interactions play a major role in estuary entrance morphodynamics and influence the degree of energy transfer from the ocean into the lagoon. This study utilizes artificial entrance openings of multiple ICOE in Victoria, Australia, to capture continuous hydrodynamic and geomorphic data throughout the opening cycle. We illustrate that water level oscillations in the infragravity (IG) band) are present in the basin during open entrance conditions. IG waves were observed to propagate up to 1.8 km upstream of the mouth while the entrance was open. Our work identifies that changes in cross‐sectional area, bed depth at the berm position, and offshore wave height control the magnitude of IG waves within the estuary basin. IG wave magnitude is also tidally modulated and increases with high tides when the nearshore water level is higher. Late during the drainage phase, waves were observed to track the margins of the channel, away from the thalweg, and reach the basin. IG wave energy was highest immediately after the basin had ceased draining and while channel dimensions at the mouth were within 10% of their maximum value. As the entrance aggrades, IG wave magnitude decreases in the absence of energetic offshore wave conditions. We relate the changes in IG wave magnitude and frequency to a six‐stage conceptual model of the opening–closure sequence. Within the basin, IG wave energy, height and frequency were also consistently highest closer to the mouth and decreased with distance upstream. Our findings indicate that water level oscillations in the IG band are a persistent feature in IOCE and may be the norm rather than the exception in these systems. As IG waves were captured serendipitously as part of a larger field campaign, future work will focus on instrumenting IOCE to gain high‐resolution data to quantify IG wave processes during entrance openings. © 2020 John Wiley & Sons, Ltd.

CALIDAD DEL AGUA DEL ESTERO EL SAUCE, VALPARAÍSO, CHILE CENTRAL

The main objective of this work was to evaluate the water quality of the El Sauce estuary and its tributaries. The El Sauce estuary basin is located in the town of Laguna Verde, Valparaíso, Central Chile. Sampling took place in the summer season of 2013 and 2015, in 11 stations located along the basin, five of them distributed from its origin to its mouth in the sea and six located before entering its tributaries. Point and non-point sources downloaded in its course were identified. The direct discharge of water from a sewage treatment plant in the area of origin of the estuary, and in its middle zone the percolation of a municipal landfill, stand out for their volume. Its mouth is affected by non-point sources of domestic waters in the town of Laguna Verde. The results show that the estuary is a shallow water course, which quality Class 4 (poor) in most of its extension presents due to the content of organic matter, nutrients, chlorides, and fecal contamination, not complying with environmental regulations for any use. There is a lack of management and control plans in the use of this important resource. It has become a risk to the community, who use the water of the stream both to irrigate subsistence agriculture and for recreation with a direct contact at its mouth.

Mitigating the Effects of Sea-Level Rise on Estuaries of the Mississippi Delta Plain Using River Diversions

Using the Mississippi River as a tool for restoration has been a key element of restoration planning in Louisiana for decades. The results of allowing river water and sediment back into the coastal system are manifested in a number of places in present day Louisiana, with additional plans for large scale sediment and water diversions from the Mississippi River. Many previous numerical modeling studies have focused on sediment delivery to Louisiana estuaries. This study examines the effects of river diversions on salinity gradients in receiving estuarine basins. The Integrated Compartment Model, a planning-level model that simulates multi-decadal change in estuarine hydrodynamics and wetland systems under assumed sea-level rise scenarios, was used to assess the estuarine salinity gradient under potential management regimes. The simulations for current conditions are compared to a future 50-year simulation with additional diversions, as well as cases with a variety of diversion options. This modeling analysis shows that without additional action, 50-years of sea-level rise could result in substantial increases in salinity throughout the Mississippi Delta Plain estuaries. This can be largely offset with additional large river diversions which can maintain variable salinity gradients throughout the estuary basins.

Offshore Platform Extraction Using RadarSat-2 SAR Imagery: A Two-Parameter CFAR Method Based on Maximum Entropy.

The ability to determine the number and location of offshore platforms is of great significance for offshore oil spill monitoring and offshore oil and gas development. Considering the problem that the detection threshold parameters of the two-parameter constant false alarm rate (CFAR) algorithm require manual and repeated adjustment of the during the extraction of offshore platform targets, this paper proposes a two-parameter CFAR target detection method based on maximum entropy based on information entropy theory. First, a series of threshold parameters are obtained using the two-parameter CFAR algorithm for target detection. Then, according to the maximum entropy principle, the optimal threshold is estimated to obtain the target detection results of the possible offshore platform. Finally, the neighborhood analysis method is used to eliminate false alarm targets such as ships, and the final target of the offshore platform is obtained. In this study, we conducted offshore platform extraction experiments and an accuracy evaluation using data from the Pearl River Estuary Basin of the South China Sea. The results show that the proposed method for platform extraction achieves an accuracy rate of 97.5% and obtains the ideal offshore platform distribution information. Thus, the proposed method can objectively obtain the optimal target detection threshold parameters, greatly reduce the influence of subjective parameter setting on the extraction results during the target detection process and effectively extract offshore platform targets.

Automatic Extraction of Offshore Platforms in Single SAR Images Based on a Dual-Step-Modified Model.

The quantity and location of offshore platforms are of great significance for marine oil spill monitoring and offshore oil-gas development. In the past, multiphase medium- and low-resolution optical or radar images have been used to remove the interference of ship targets based on the static position of a platform to extract the offshore platform, resulting in large demands and high image data costs. According to the difference in shape between offshore platforms (not elongated) and ships (elongated shapes) in SAR (synthetic aperture radar) images, this paper proposes an automatic extraction method for offshore platforms in single SAR images based on a dual-step-modified model. First, the two-parameter CFAR (constant false alarm rate) algorithm was used to detect the possible offshore platform targets; then, the Hough transform was introduced to detect and eliminate ship targets with linear structures. Finally, the final offshore platform was obtained. Experiments were carried out in four study areas in the Beibu Gulf basin and the Pearl River estuary basin in the northern South China Sea. The results show that the method has a good extraction effect in the above research area, and the extraction accuracy rate of offshore platforms is 86.75%. A single SAR image can obtain satisfactory extraction results, which greatly saves on image data cost.

ECONOMIC ACTIVITY CONCEPTUAL APPROACHES OF DIVERSITY ACTIVATION IN THE KUYALNIK ESTUARY ZONE

Topicality. Current high socioeconomic (public) request for recreational and tourist services and the inadequate use of available natural resources in Ukraine as recreational make it necessary to find directions for diversification of their rational use for expanding recreational and tourist activities and related species.Aim and tasks. Purpose of the article is to determine the conceptual approaches to the diversification processes development in the use of natural resources around the territory of Kuyalnitsky estuary, that are aimed at revealing its potential and expansion of business activities of enterprises and districts in general.Research results. According to the analysis of financial and economic indicators of administrative units (Bilyaivskyi, Ivanivsky and Limansky districts), adjacent to the Kuyalnitsky estuary, and the aim, the authors conclude that the traditional use of natural resources in agriculture and industry does not provide the proper level of socio-economic development of the districts and they are not financially self-sufficient. Consequently, the economic activity in the Kuyalnitsky estuary basin is focused on agriculture and industrial production, but this territory diversification of the natural resource potential use in the direction of recreational and tourist activity as an alternative to existing types of production is required. The processes of diversification will consist in the production of environmentally friendly products and services to meet the needs of recreational activities, as recreational activity will contribute to increasing demand for them. To start diversification of economic activities types, which will provide synergistic effect and increase economic indicators of the development of areas around the Kuyalnitsky estuary is proposed. Among the areas of natural resources diversification of the estuary, it is proposed to consider the development of a network of sanatorium and resort establishments, enterprises of cosmetic products creation, as well as beauty salons with the use of the resource potential of the Kuyalnitsky estuary (brine, mud, salt, blue clay, phyto-preparations).Conclusions. The districts located around the Kuyalnitsky estuary have rich recreational natural resources, but do not use them fully in economic activity. In fact, there is only one sanatorium that uses mud and peloids of the estuary. The budgets of these districts do not cover their expenditures and receive subsidies from the regional budget, and the lack of proper implementation of the environmental legislation has led to the almost critical environmental situation of the Kuyalnitsky estuary. In order to improve the current situation, the authors propose to direct economic activities diversification processes of economic entities for the tourism development, in particular, rural, green, ecological, cognitive with the provision of medical services on the basis of unique mud of the estuary, taking into account ecosystem and polyfunctional approaches that will ensure the use , preservation and protection of a unique natural object.