Coastal Water Environment Research Articles

TOTAL SUSPENDED SOLID DISTRIBUTION IN HAU RIVER USING SENTINEL 2A SATELLITE IMAGERY

Abstract. This research was applied high-resolution Sentinel-2A imagery which aims to monitor a suitability of MultiSpectral Imager (MSI) at higher resolution (10 m) for mapping of Total Suspended Solids (TSS) ) in the upper reaches of the Mekong Delta – An Giang province. The field survey is carried out to collect TSS at random distribution sites outside full-dyke protection. A remote sensing algorithm with a regression function method is developed to estimate TSS concentration automatically to select between the most sensitive TSS and water reflectance relationship. The regression analytical algorithm is predicted the output values based on normalized suspended material index (NSMI) (r2 = 0.92), showing the MSI sensor’s great potential to estimate TSS. The results confirm that suspended materials in the surface water reached the minimum of 10.36 mg/l and the maximum of 328.56 mg/l in An Giang province, the suspended materials distributional tendency with high content was mainly in flooded fields near the upstream of the basin of Hau river, especially in areas without the dike enclosure and the content was low in the areas within the dike enclosure. These findings promote further research in water quality studies relying on both operational Sentinel-2A and Sentinel-2B imageries with great implications to improve the understanding of turbid coastal and inland water environments.

Extensions of the river plume under various Yellow River courses into the Bohai Sea at different times

River plumes are formed when riverine freshwater spreads out over underlying saline oceanic water, influencing the water properties, circulation, marine ecological environment and fishery resources in the adjacent coastal waters. The Yellow River is the largest river that flows into the Bohai Sea, and since 1964 it has shifted its course three times. A 3-D numerical model was used to study the extensions of the Yellow River plume under the three river courses into the sea at three different times in its recent past, together with their seasonal variations. The residual water flux was calculated to better represent the net water transport in the shallow waters over individual tides. During the Diaokou course (c.1976), the river plume spread out near the river mouth and slightly deflected northwards in winter, while extending far southeastwards into the central part of the Bohai Sea in summer. During the Qingshuigou course (c.1996), the river plume was restricted within Laizhou Bay in both winter and summer under the Coriolis and buoyancy forces induced by the salinity front. During the Q8 course (c.2017), the river plume was confined within Laizhou Bay during winter while part of the river plume extended into Laizhou Bay and part of it extended into the central area of the Bohai Sea due to the eastward Ekman transport produced by the southerly wind in summer. The effects of wind, ambient current, bathymetric change, and river discharge on the extension of the Yellow River plume at different times in its recent history are systematically analyzed and discussed. The simulated clear differences of the river plume extensions under various courses of the river into the Bohai Sea at different times is fundamental for the better understanding and protection of the fishery resources.

Does Coastal Local Government Competition Increase Coastal Water Pollution? Evidence from China.

China has formulated many policies and regulations for the management of the coastal water environment. However, the coastal water environment has not been significantly improved. The perspective of local government competition can provide an explanation for this phenomenon. This study uses panel data comprising 48 coastal cities in China from 2004 to 2017 as bases explore the impact of coastal local government competition on coastal water pollution by using a two-way fixed-effects panel regression model. Results show that coastal local government competition increased coastal water pollution. However, a sub-sample estimation based on fiscal pressure shows that coastal local government competition only increased the coastal water pollution of the high fiscal pressure group, and its impact on the coastal water pollution in the low financial pressure group failed to pass the significance test. In addition, sub-sample estimation based on different periods shows that the impact of coastal local government competition on coastal water pollution was not significant before 2008, but showed a significant positive impact after 2008.

Countermeasures for Marine Environmental Pollution Governance: An Ecological Civilization Perspective

Chen, X. and Zheng, J., 2020. Countermeasures for marine environmental pollution governance: An ecological civilization perspective. In: Gong, D.; Zhang, M., and Liu, R. (eds.), Advances in Coastal Research: Engineering, Industry, Economy, and Sustainable Development. Journal of Coastal Research, Special Issue No. 106, pp. 355–358. Coconut Creek (Florida), ISSN 0749-0208.The smooth implementation and development of the marine strategy cannot be separated from the protection of the marine ecological environment. With the increase of marine utilization in China, the problem of marine environmental pollution is more and more serious. Therefore, it is urgent to carry out research into countermeasures for marine environmental pollution control based on the perspective of ecological civilization. This paper first introduces the theoretical basis of marine environmental pollution control based on ecological civilization, then gives the status of the marine ecological environment in China's coastal waters, and then analyzes the status of marine ecological environment control in China. Finally, this paper gives suggestions on the specific strategies for marine environmental pollution control based on ecological civilization.

Rapid Sampling of Suspended and Floating Microplastics in Challenging Riverine and Coastal Water Environments in Japan

Environmental sampling plays an important role in quantitative and qualitative investigation of plastic pollution. Rivers are a major source, carrying plastic litter into the oceans. Microplastic sampling in riverine and coastal environments is often a challenging task due to limited access, time taken, costs, human resources, etc. Our present study evaluated the performance of newly developed sampling devices (Albatross Mark 5 and 6 (AM-5 and AM-6)) that were suitable to collect floating and suspended microplastic samples in challenging freshwater and coastal environments (95 locations). Our observations indicated a similar magnitude of microplastic concentrations with AM-5 and AM-6 sampling compared to conventional plankton nets. The sampling duration, originally 10–60 min (by plankton net), was reduced to 3 min (AM-5 and AM-6) for sampling water volumes of approximately 10 m3. The developed AM-6 device was used to collect samples from riverine and coastal environments in Japan. The microplastic particle polymer composition (using Fourier transform infrared spectrophotometry (FT-IR)), size, and shape (microscopic images) were investigated. The observations showed a statistically significant particle size reduction from the riverine to coastal areas. The dominant polymer types detected were polyethylene (PE) and polypropylene (PP). The observations were complied with the coastal microplastic observations that were reported for previous studies in Japanese water environments.

A review of approaches for water depth estimation with multispectral data

AbstractThe purpose of this paper is to give an exhaustive assessment of water depth estimation in shallow inland and coastal water environments with the assistance of optical remote detecting procedures, utilizing satellite/airborne multispectral information. Remote sensing has been used to map bathymetry for several decades. Inaccessibility, large‐scale depth mapping, very shallow areas, and cost constraint are some of the reasons why remote sensing technique is a boon for bathymetry. Researchers have come a long way since the remote sensing‐based bathymetry has been used. Fourfold increase in spatial, spectral, radiometric and temporal resolution of sensors have also increased the accuracy. There are two types of remote sensing techniques; Active and Passive. Active remote sensing includes the use of ground penetrating radar and bathymetric lidar, which are expensive but precise surveys successful up to 70 m depth. On the other hand, passive remote sensing deals with water photogrammetry and radiometric methods done by capturing imagery with space borne/air borne platforms having depth penetration up to 25 m. The latter technique includes finding of a logarithmic relationship between river depth and image values. This technique is most widely used because of its cost effectiveness. In this paper, the emphasis has been given to derive bathymetric techniques using multispectral data as these methods have proved reasonably successful when water quality, bottom reflectance, and atmospheric effects are all invariant. At a specific area, the detection of possible changes in water flow and levels indicates flow path changes which can be used to predict potential surface level flooding for better water management and policy decisions.

Total Maximum Allocated Load of Chemical Oxygen Demand Near Qinhuangdao in Bohai Sea: Model and Field Observations

Total maximum allocated load (TMAL) is the maximum sum total of all the pollutant loading a water body can carry without surpassing the water quality criterion, which is dependent on hydrodynamics and water quality conditions. A coupled hydrodynamic and water quality model combined with field observation was used to study pollutant transport and TMAL for water environment management in Qinhuangdao (QHD) sea in the Bohai Sea in northeastern China for the first time. Temporal and spatial variations of the chemical oxygen demand (COD) concentration were investigated based on MIKE suite (Danish Hydraulic Institute, Hørsholm, Denmark). A systematic optimization approach of adjusting the upstream pollutant emission load was used to calculate TMAL derived from the predicted COD concentration. The pollutant emission load, TMAL, and pollutant reduction of Luanhe River were the largest due to the massive runoff, which was identified as the most influential driving factor for water environmental capacity and total carrying capacity of COD. The correlation analysis and Spearman coefficient indicate strong links between TMAL and forcing factors such as runoff, kinetic energy, and pollutant emission load. A comparison of total carrying capacity in 2011 and 2013 confirms that the upstream pollutant control scheme is an effective strategy to improve water quality along the river and coast. Although, the present model results suggest that a monitoring system could provide more efficient total capacity control. The outcome of this study establishes the theoretical foundation for coastal water environment management strategy in this region and worldwide.

An ultraviolet to visible scheme to estimate chromophoric dissolved organic matter absorption in a Case-2 water from remote sensing reflectance

In a typical Case-2 coastal water environment (here, the Pearl River Estuary (PRE), China), chromophoric dissolved organic matter (CDOM) and suspended particulates dominate the water optical properties, and CDOM fluorescence contributes considerably to surface water reflectance. In this paper, an ultraviolet (UV) to visible scheme to retrieve CDOM absorption (ag)is developed based on a set of in situ observations. First, the CDOM UV absorption and spectral slope (Sg) are derived directly from the visible remote sensing reflectance; then the Sg is extrapolated to obtain the spectrum from UV to visible spectral range. This algorithm performs well, with an overall mean absolute percent difference (MAPD) of ∼30%, ∼5% and ∼6% for the estimation of ag in 250–450 nm, Sg over 250–400 nm, and 250–700 nm, respectively. The effectiveness and stability of the algorithm is further demonstrated in capturing the distribution pattern of CDOM absorption in the PRE from satellite ocean color imagery with multiple spatial and spectral resolution, namely: the Visible Infrared Imaging Radiometer Suite (VIIRS) (750 m/Multispectral), the Ocean and Land Color Instrument (OLCI) (300 m/Multispectral), the Hyperspectral Imager for the Coastal Ocean (HICO) (100 m/Hyperspectral), and the Landsat 8 Operational Land Imager (OLI) (30 m/Multispectral). The UV to visible scheme can benefit the CDOM absorption estimation in two aspects: 1) it is free from the disturbance of suspended matter; 2) it avoids uncertainties caused by the low signal-to-noise ratio (SNR) of ag measurements in the visible range. The algorithm is effective in revealing multiple scales of variation of CDOM absorption from ocean color observations.

Coastal resource-environmental carrying capacity assessment: A comprehensive and trade-off analysis of the case study in Jiangsu coastal zone, eastern China

The coastal zone is the key area for sustainable scientific research and realizing the strategic development of China's economic and ecological goals. As one of the regions with the highest human activity, the coordinated development of its ecological environment and social economy cannot be ignored. Based on the study of the relationship between ecological environment quality and socio-economic development, this paper proposed the Coastal Resource-environmental Carrying Capacity (CRECC) which including three subsystems (the Resource's system, the Ecological system, and the Socio-economical system), as well as 6 first-level indices and 20 s-level indicators. The entropy weight method and analytic hierarchy process were used to calculate the average weight, and the changing rate of carrying capacity value was analyzed based on the ordinary least square method. Taking the coastal zone of Jiangsu Province as the study area, we calculated the changes of comprehensive/subsystems' carrying capacity from 2000 to 2015, and the trade-off relationship within the subsystem was analyzed. From 2000 to 2015, the value of CRECC, the Resource's system, and the Socio-economical system decreased while the Ecological system's value showed a volatility rise. Overall, the regional carrying capacity level was low. However, positive environmental management measures have significantly improved the status of the ecological environment and helped to alleviate the environmental pressure brought by population growth. the Ecological system played an important role in the change of regional carrying capacity. Vegetation coverage, coastal water environment quality index, tidal flat reclamation area, habitat, and ecological land proportion are significant influencing factors. This also indicated that the landscape ecological status, offshore water quality and utilization of space resources in Jiangsu coastal zone aren't sustainable. Therefore, it is recommended to improve the ecological resilience of coastal zones, such as implementing spatial planning of tidal flat resources, and controlling pollutant discharge, etc. in order to promote the regional sustainable development.

Factors Determining Benthic Foraminiferal Distribution in the Shallow Water Coastal Environments of Southwest Nigeria Sector of the Gulf of Guinea

Factors Determining Benthic Foraminiferal Distribution in the Shallow Water Coastal Environments of Southwest Nigeria Sector of the Gulf of Guinea

Description of a new toothed mysticete from the Late Oligocene of San Juan de La Costa, B.C.S., México

This paper describes a toothed mysticete that belongs to a basal family found in Oligocene sedimentary rocks deposited in the North Pacific Ocean. The material that is described here belongs in the Chattian stage of the Oligocene, and it was collected near Arroyo El Saladito from the San Juan Member in the El Cien Formation, Baja California Sur, México. The sedimentary environment of this area has been interpreted to be a continental platform with nutrient-rich waters combined with anoxic conditions. Therefore, the specimens that have been found in the phosphorite layers lived in an environment of shallow coastal waters. The material described is a dentary fragment, a skull and fragments of the teeth. The new taxon is located within the Superfamily Aetiocetoidea due to the presence of functional teeth, which have a slightly globose shape with eight slightly triangular apices. Niparajacetus palmadentis presents a morphology that contrasts with other toothed whales. For example, it shows an elongated and wide skull in the posterior region with a triangular shape, and its estimated total length is 3.2–3.5 m.

The influence of environmental conditions onParasagitta friderici(Chaetognatha) abundance in a subtropical estuary (south Brazil)

AbstractEstuarine chaetognath population dynamics are poorly known worldwide. We have conducted eight seasonal campaigns (October 2007–August 2008) sampling three sectors in the subtropical Babitonga Bay estuary (26°S 48°W) in order to depict chaetognath abundance and population structure dynamics and test the influence of hydrography and food availability and type. Of three species sampled,Parasagitta fridericirepresented >93% of abundance in all samples and was examined in detail. There were no differences inP. fridericiabundance between the sectors of the estuary, related to its high tolerance to low salinity, a feature not common for most chaetognath species. Salinity tolerance is an important adaptive characteristic to thrive within estuarine systems, and probably is responsible for the dominance ofP. fridericiin coastal and brackish water environments throughout most of its distribution. Juveniles dominated the population most of the year, except in February–April when abundances were lower and adults predominated. These results suggest that recruitment occurs continuously throughout the year, being more intense between October and January (spring to early summer) and in May (autumn) when densities and proportion of juveniles were higher. General Additive Models suggest that temperature and zooplankton biomass are significant (P< 0.05) factors influencing juvenile abundance while only the latter influenced the adults. We conclude that food availability is the most important driver in the studied population ofP. fridericiand recruitment peaks, which lead to high densities, seem to occur following peaks of their copepod prey along with particular temperature conditions (22–23°C).

Evaluation of the First Year of Operational Sentinel-2A Data for Retrieval of Suspended Solids in Medium- to High-Turbidity Waters

In this study, we apply high-resolution Sentinel-2A imagery to assist in the monitoring of the southwestern Spanish coast during its first year of data. The aim is to test suitability of MultiSpectral Imager (MSI) at higher resolution (10 m) for mapping Total Suspended Solids (TSS). Several field campaigns are carried out to collect TSS at three different sites in the Guadalquivir estuary, Cadiz Bay and Conil port. A regional multi-conditional remote sensing algorithm with a switching method that automatically selects the most sensitive TSS vs. water reflectance relationship is developed to estimate TSS concentration while avoiding saturation effects. An existing semi-analytical algorithm is calibrated by means of a cross-validation procedure based on both red 664 nm (r = 0.8, NRMSE of 25.06%) and near-infrared (NIR) 865 nm (r = 0.98, NRMSE of 10.28%) parts of the spectrum, showing the MSI sensor’s great potential to estimate TSS even though it was not designed for aquatic remote sensing. The first year of data reveals improved monitoring along the coastal region at unprecedented resolution with accuracy to detect the Estuarine Turbidity Maximum (ETM). ACOLITE and POLYMER Atmospheric Correction strategies are applied over this coastal region (no in-situ data on water reflectance). The results confirm that the flexible POLYMER algorithm can address intense sun-glint effects. These findings encourage further research of water quality studies relying on both operational Sentinel-2A and Sentinel-2B, with great implications to improve the understanding of turbid coastal and inland water environments.

Distributed system of autonomous buoys for scalable deployment and monitoring of large waterbodies

The design, construction, and testing of a large distributed system of novel, small, low-cost, autonomous surface vehicles in the form of self-propelled buoys capable of operating in open waters is reported. We detail the successful testing of collective behaviors of systems with up to 50 buoys, achieving scalable deployment and dynamic monitoring in unstructured environments. This constitutes the largest distributed multi-robot system of its kind reported to date. We confirm the robustness of the system to the loss of multiple units for different collective behaviors such as flocking, navigation, and area coverage. For dynamic area monitoring, we introduce a new metric to quantify coverage effectiveness. Our system exhibits near optimal scalability for fixed target areas and a high degree of flexibility when the shape of the target changes with time. This system demonstrates the potential of distributed multi-robot systems for the pervasive and persistent monitoring of coastal and inland water environments.

Holocene Ostracoda (Crustacea) from the shallow Lake Vrana (Dalmatia, Croatia) and their paleoenvironmental significance

Lake Vrana in Dalmatia is a coastal karstic brackish water environment characterized by a high species richness of ostracods that evolved into their current morphologies during the Holocene. The results of this study reveal five ostracod zones within an 11 m sediment core taken from the central part of the lake. This sedimentary sequence reveals significant changes in both depositional and environmental conditions at local and regional scales; the oldest freshwater deposits, interpreted as the Late Pleistocene/Holocene transition, mainly comprise the species Candona neglecta, Juxilyocypris cf. schwarzbachi, Hungarocypris madaraszi, Darwinula stevensoni, and Mixtacandona sp. Although the lake had not formed at this time, it is well known that the living environment of most ostracod species is connected to flooded plains, marshes, rivers, springs, and interstitial waters. In the deepest and oldest sediments within the core, from depths between 1101 cm and 945 cm, the presence of C. neglecta and J. cf. schwarzbachi are indicative of cold water, while the dominant taxa at depths between 945 cm and 874 cm are the brackish species Cyprideis torosa and C. angulata, possibly suggesting the influence of seawater because of the presence of a permeable karstic ridge that separates the lake from the ocean. In contrast, the dominant ostracod taxa at depths between 874 cm and 813 cm are species typical of freshwater environments subject to colder climatic conditions indicating a marshy, low-energy wetland. We know that the first permanent freshwater body formed at about 8130 cal yr BP (a depth of 813 cm), while large proportions of Pseudocandona marchica, Heterocypris salina, D. stevensoni, and Metacypris cordata are all indicative of warmer, shallow waters that are rich in vegetation and have variable water level. Similarly, from 5240 cal yr BP onwards, a marine influence within the core is evidenced by the presence of Cy. torosa, while present lake water conditions (i.e., alternating seasonal changes in salinity from freshwater to brackish) were established by 2750 cal yr BP. The ostracod assemblages in sediments from Lake Vrana in Dalmatia have significant potential for reconstructing the evolution of this lake as well as for understanding environmental changes and rising sea level.

Coastal water environment regulation and simulation based on tidal power control

As the carrier of water resources, water environment and water ecology, river course is very important to human and ecological environment in coastal areas. The rapid economic development of coastal areas needs to take into account the improvement of regional water environment in order to achieve a higher level of development. The characteristics of coastal water environment are closely related to tidal fluctuation. It is an important direction for coastal water control to improve the water environment and restore the self-purification capacity of the river by guiding and draining the tidal power. In this paper, the YACHONG River Basin, which borders Macau and Zhuhai, is selected as the study area. The semi-exchange period and water exchange rate are taken as the main evaluation indexes. The water quantity and quality model is used to simulate the scenario model and analyze the effect of water diversion and drainage regulation in different tidal periods. The results show that, compared with the drainage dispatch during spring tide, the drainage dispatch during neap tide prolongs the water exchange time, and the effect of water exchange is obviously better than that during spring tide. The research results of this paper provide reference for water environmental regulation in coastal area.

Suitability Evaluation of Sea Area Utilization in the Land Sea Integration Strategy

Suitability evaluation of sea area utilization is a key process in marine functional zoning. Evaluation focused on sea area conditions is facing the challenges from rapid social economic development. This article discussed the challenges of suitability evaluation of sea area utilization, provided a conception of suitability evaluation of sea area utilization in the land sea integration strategy, and pointed out the key steps to achieve it. It was concluded that current suitability evaluations of sea area utilization were facing the challenges of serious deterioration of coastal water environment, changing social economic conditions on land and achieving goals of ecosystem management. Suitability evaluation of sea area utilization in the land sea integration strategy is a good practice to solve these problems. Land sea integration zones and spatial distribution simulation of social economic factors are key steps of suitability evaluation of sea area utilization in the land sea integration strategy.

Analysis of recent coastline evolution due to marine reclamation projects in the Qinzhou Bay

Abstract Intense marine reclamation activities bring obvious benefits, meanwhile, these activities also influence the coastal natural formation, hydrodynamic processes and water environment etc. In order to investigate the exact influence in the Qinzhou Bay brought by marine reclamation behaviors in recent years, based on the remote sensing image data in the Qinzhou Bay in 2006, 2008, 2009, 2012 and 2014, with the help of GIS and RS software, the thesis interprets Qinzhou Bay coastline and artificial reclamation by man-machine interaction and makes quantitative analysis in the Qinzhou Bay coast evolution recently. The results show: (1) Qinzhou Bay coastal morphology change degree was strong in 2006 - 2012 and the coastline changed greatly. Originally part of the natural shore segments which had twists and turns were gradually filled into artificial coast, the coast constantly advanced to the sea, coastline became regular and straight; (2) The change degree of coastline was relatively small in 2006-2008, the average artificial coastline increased 8.86 km/a, the average artificial reclamation area was 20.79 km2 /a; in 2008-2012, the change range of coastline was the greatest, coastline changed most severely, the average artificial coastline increased 16.07 km/a, the average artificial reclamation area was 58.52 km2 /a; however, in 2012-2014, coastline change degree relatively slowed, the average artificial coastline increased 4.04 km per year, the average artificial reclamation area was 3.464 km2 /a. (3) Compared to the studies of predecessors, the innovation of this paper is that it is the first to carry out the detailed research on coastline evolution caused by reclamation engineerings of the Qinzhou Bay, then formed the change results on coastline that caused by intense human activities in the Qinzhou Bay, provided the area of the marine environment protection with full and accurate data.

Influence of a water regulation event on the age of Yellow River water in the Bohai

Abrupt changes in freshwater inputs from large rivers usually imply regime shifts in coastal water environments. The influence of a water regulation event on the age of the Yellow River water in the Bohai was modeled using constituent-oriented age and residence time theory to better understand the change in the environmental function of the hydrodynamic field owing to human activities. The water ages in Laizhou Bay, the central basin, and the Bohai strait are sensitive to water regulation. The surface ages in those areas can decrease by about 300 days, particularly in July, and the age stratification is also strengthened. A water regulation event can result in declines in the water age in early July ahead of declines in the water age under climatological conditions (without the regulation event) by about 1 and 5 months in the central basin and Laizhou Bay, respectively. The change in the coastal circulation due to the water regulation event is the primary reason for the change in the Yellow River water age. The high Yellow River flow rate can enhance the density flow and, therefore, reduce the age of the Yellow River water. The subsequent impact of a single water regulation event can last about 1.0 to 4.0 years in different subregions.

Impact of wet season river flood discharge on phytoplankton absorption properties in the southern Great Barrier Reef region coastal waters

Light absorption due to particulate and dissolved material plays an important role in controlling the underwater light environment and the above water reflectance signature. Thorough understanding of absorption properties and their variability is important to estimate light propagation in the water column. However, knowledge of light absorption properties in flood impacted coastal waters is limited. To address this knowledge gap we investigated a bio-optical dataset collected during a flood (2008) in the southern Great Barrier Reef (GBR) region coastal waters. Results presented here show strong impact of river flood discharges on water column stratification, distribution of suspended substances and light absorption properties in the study area. Bio-optical analysis showed phytoplankton absorption efficiency to reduce in response to increased coloured dissolved organic matter presence in flood impacted coastal waters. Biogeophysical property ranges, relationships and parametrisation presented here will help model realistic underwater light environment and optical signature in flood impacted coastal waters.