scholarly journals Continuous Change Mapping to Understand Wetland Quantity and Quality Evolution and Driving Forces: A Case Study in the Liao River Estuary from 1986 to 2018

2021 ◽  
Vol 13 (23) ◽  
pp. 4900
Author(s):  
Jianwei Peng ◽  
Shuguang Liu ◽  
Weizhi Lu ◽  
Maochou Liu ◽  
Shuailong Feng ◽  
...  
Keyword(s):  
Coastal Wetlands ◽  
Coastal Wetland ◽  
Driving Forces ◽  
Land Reclamation ◽  
River Estuary ◽  
Tidal Flats ◽  
Liaoning Province ◽  
Coastal Zones ◽  
Continuous Change ◽  
Landsat Images

Coastal wetland ecosystems, one of the most important ecosystems in the world, play an important role in regulating climate, sequestering blue carbon, and maintaining sustainable development of coastal zones. Wetland landscapes are notoriously difficult to map with satellite data, particularly in highly complex, dynamic coastal regions. The Liao River Estuary (LRE) wetland in Liaoning Province, China, has attracted major attention due to its status as Asia’s largest coastal wetland, with extensive Phragmites australis (reeds), Suaeda heteroptera (seepweed, red beach), and other natural resources that have been continuously encroached upon by anthropogenic land-use activities. Using the Continuous Change Detection and Classification (CCDC) algorithm and all available Landsat images, we mapped the spatial–temporal changes of LRE coastal wetlands (e.g., seepweed, reed, tidal flats, and shallow marine water) annually from 1986 to 2018 and analyzed the changes and driving forces. Results showed that the total area of coastal wetlands in the LRE shrank by 14.8% during the study period. The tidal flats were the most seriously affected type, with 45.7% of its total area lost. One of the main characteristics of wetland change was the concurrent disappearance and emergence of wetlands in different parts of the LRE, creating drastically different mixtures of wetland quality (e.g., wetland age composition) in addition to area change. The reduction and replacement/translocation of coastal wetlands were mainly caused by human activities related to urbanization, tourism, land reclamation, and expansion of aquaculture ponds. Our efforts in mapping annual changes of wetlands provide direct, specific, and spatially explicit information on rates, patterns, and causes of coastal wetland change, both in coverage and quality, so as to contribute to the effective plans and policies for coastal management, preservation, and restoration of coastal ecosystem services.

Study on the Loss and Degradation and Sustainable Development Countermeasures of the Coastal Wetlands in Qinhuangdao

2013 ◽  
Vol 361-363 ◽  
pp. 1016-1019
Author(s):  
Yan Dong Peng ◽  
Jing Yue Wang
Keyword(s):  
Sustainable Development ◽  
Coastal Wetlands ◽  
Coastal Wetland ◽  
Land Reclamation ◽  
Port Development ◽  
Natural Factors ◽  
Sandy Coast ◽  
Main Factors ◽  
Development Countermeasures ◽  
Rocky Coast

Qinhuangdao coastal wetland is the distribution of China's most representative of the sandy coastal wetlands, and its main wetland types are sandy coast wetland, rocky coast wetland, estuarine wetland, lake wetland, shallow sea wetland and artificial wetland. Under the influence of natural factors and human factors, coastal wetlands degradation constantly. Land reclamation, city and port development, pollution, coastal erosion and excessive use of coastal biologic resource are considered as the main factors to the degradation of the coastal wetlands. Based on the analysis the main factors contributing to the loss and degradation of the coastal wetlands and the characteristics of wetland degradation, sustainable development countermeasures are suggested in this paper.

scholarly journals Evolutions of 30-Year Spatio-Temporal Distribution and Influencing Factors of Suaeda salsa in Bohai Bay, China

2021 ◽  
Vol 14 (1) ◽  
pp. 138
Author(s):  
Hongyan Yin ◽  
Yuanman Hu ◽  
Miao Liu ◽  
Chunlin Li ◽  
Yu Chang
Keyword(s):  
Influencing Factors ◽  
Coastal Wetlands ◽  
Yellow River ◽  
River Estuary ◽  
Google Earth ◽  
River Delta ◽  
Liaoning Province ◽  
Suaeda Salsa ◽  
Bohai Bay ◽  
Dynamic Changes

Suaeda salsa (L.) Pall. (S. salsa) acts as a pioneer species in coastal wetlands due to its high salt tolerance. It has significant biodiversity maintenance, socioeconomic values (e.g., tourism) due to its vibrant color, and carbon sequestration (blue carbon). Bohai bay region, the mainly distributed area of S. salsa, is an economic intensive region with the largest economic aggregate and population in northern China. The coastal wetland is one of the most vulnerable ecosystems with the urbanization and economic developments. S. salsa in Bohai Bay has been changed significantly due to several threats to its habitat in past decades. In this paper, we analyzed all available archived Landsat TM/ETM+/OLI images of the Bohai Bay region by using a decision tree algorithm method based on the Google Earth Engine (GEE) platform to generate annual maps of S. salsa from 1990 to 2020 at a 30-m spatial resolution. The temporal-spatial dynamic changes in S. salsa were studied by landscape metric analysis. The influencing factors of S. salsa changes were analyzed based on principal component analysis (PCA) and a logistic regression model (LRM). The results showed that S. salsa was mainly distributed in three regions: the Liao River Delta (Liaoning Province), Yellow River Delta (Shandong Province), and Hai River Estuary (Hebei Province, Tianjin). During the past 31 years, the total area of S. salsa has dramatically decreased from 692.93 km2 to 51.04 km2, which means that 92.63% of the area of S. salsa in the Bohai Bay region was lost. In the 641.89 km2 area of S. salsa that was lost, 348.80 km2 of this area was converted to other anthropic land use categories, while 293.09 km2 was degraded to bare land. The landscape fragmentation of S. salsa has gradually intensified since 1990. National Nature Reserves have played an important role in the restoration of suitable S. salsa habitats. The analysis results for the natural influencing factors indicated that precipitation, temperature, elevation, and distance to the coastline were considered to be the major influencing factors for S. salsa changes. The results are valuable for monitoring the dynamic changes of S. salsa and can be used as effective factors for the restoration of S. salsa in coastal wetlands.

Updating global coastal wetland areas presented in Davidson and Finlayson (2018)

2019 ◽  
Vol 70 (8) ◽  
pp. 1195 ◽  
Author(s):  
Nick C. Davidson ◽  
C. Max Finlayson
Keyword(s):  
Salt Marshes ◽  
Coastal Wetlands ◽  
Coastal Wetland ◽  
Tidal Flats ◽  
Seagrass Beds ◽  
Wetland Area

Global and regional areas and trends in area of unvegetated tidal flats, salt marshes, mangroves and seagrass beds are updated and corrected from those published in Davidson and Finlayson (2018). The global area of coastal wetlands is now estimated as a minimum of 1.42×106 km2, ~8.9–9.5% of an updated global wetland area of 15.0×106–16.0×106 km2.

scholarly journals Assessing the Ecosystem Health of Coastal Wetland Vegetation (Suaeda salsa) Using the Pressure State Response Model, a Case of the Liao River Estuary in China

2022 ◽  
Vol 19 (1) ◽  
pp. 546
Author(s):  
Ziming Song ◽  
Yingyue Sun ◽  
Peng Chen ◽  
Mingming Jia
Keyword(s):  
Coastal Wetland ◽  
Anthropogenic Impacts ◽  
River Estuary ◽  
Liaoning Province ◽  
Suaeda Salsa ◽  
State Response ◽  
Aquaculture Ponds ◽  
Tourism Resource ◽  
Original Vegetation ◽  
Pressure State

Suaeda salsa (S. salsa) is an important ecological barrier and tourism resource in coastal wetland resources, and assessing changes in its health is beneficial for protecting the ecological health of wetlands and increasing finances. The aim was to explore improvements in the degradation of S. salsa communities in the Liao River Estuary National Nature Reserve since a wetland restoration project was carried out in Panjin, Liaoning Province, China, in 2015. In this study, landscape changes in the reserve were assessed based on Sentinel-2 images classification results from 2016 to 2019. A pressure-state-response framework was constructed to assess the annual degradation of S. salsa communities within the wetlands. The assessment results show that the area of S. salsa communities and water bodies decreased annually from 2016 to 2019, and the increased degradation indicators indicate a state of continued degradation. The area of types such as aquaculture ponds and Phragmites australis communities did not change much, while the estuarine mudflats increased year by year. The causes of S. salsa community degradation include anthropogenic impacts from abandoned aquaculture ponds and sluice control systems but also natural impacts from changes in the tidal amplitude and soil properties of the mudflats. The results also indicate that the living conditions of S. salsa in the Liao River estuary wetlands are poor and that anthropogenic disturbance is necessary to restore the original vegetation abundance.

scholarly journals SPATIO-TEMPORAL CHANGE OF VEGETATION COVERAGE AND ITS DRIVING FORCES BASED ON LANDSAT IMAGES: A CASE STUDY OF CHANGCHUN CITY

2018 ◽  
Vol XLII-3 ◽  
pp. 295-298 ◽  
Author(s):  
L. Dong ◽  
H. Jiang ◽  
L. Yang
Keyword(s):  
Vegetation Change ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Driving Forces ◽  
Land Reclamation ◽  
Research Area ◽  
Vegetation Coverage ◽  
Landsat Images ◽  
Temperature And Precipitation ◽  
Spatio Temporal

Based on the Landsat images in 2006, 2011 and 2015, and the method of dimidiate pixel model, the Normalized Difference Vegetation Index (NDVI) and the vegetation coverage, this paper analyzes the spatio-temporal variation of vegetation coverage in Changchun, China from 2006 to 2015, and investigates the response of vegetation coverage change to natural and artificial factors. The research results show that in nearly 10 years, the vegetation coverage in Changchun dropped remarkably, and reached the minimum in 2011. Moreover, the decrease of maximum NDVI was significant, with a decrease of about 27.43 %, from 2006 to 2015. The vegetation coverage change in different regions of the research area was significantly different. Among them, the vegetation change in Changchun showed a little drop, and it decreased firstly and then increased slowly in Yushu, Nong’an and Dehui. In addition, the temperature and precipitation change, land reclamation all affect the vegetation coverage. In short, the study of vegetation coverage change contributes scientific and technical support to government and environmental protection department, so as to promote the coordinated development of ecology and economy.

Coastline Vulnerability Assessment through Landsat and Cubesats in a Coastal Mega City

2020 ◽  
Vol 12 (5) ◽  
pp. 749 ◽  
Author(s):  
Majid Nazeer ◽  
Muhammad Waqas ◽  
Muhammad Imran Shahzad ◽  
Ibrahim Zia ◽  
Weicheng Wu
Keyword(s):  
Spatial Resolution ◽  
Land Reclamation ◽  
Anthropogenic Activities ◽  
Monsoon Season ◽  
Coastal Protection ◽  
Landsat Images ◽  
Intergovernmental Panel ◽  
Eastern Zone ◽  
Stable Conditions ◽  
Western Zone

According to the Intergovernmental Panel on Climate Change (IPCC), global mean sea levels may rise from 0.43 m to 0.84 m by the end of the 21st century. This poses a significant threat to coastal cities around the world. The shoreline of Karachi (a coastal mega city located in Southern Pakistan) is vulnerable mainly due to anthropogenic activities near the coast. Therefore, the present study investigates rates and susceptibility to shoreline change using a 76-year multi-temporal dataset (1942 to 2018) through the Digital Shoreline Analysis System (DSAS). Historical shoreline positions were extracted from the topographic sheets (1:250,000) of 1942 and 1966, the medium spatial resolution (30 m) multi-sensor Landsat images of 1976, 1990, 2002, 2011, and a high spatial resolution (3 m) Planet Scope image from 2018, along the 100 km coast of Karachi. The shoreline was divided into two zones, namely eastern (25 km) and western (29 km) zones, to track changes in development, movement, and dynamics of the shoreline position. The analysis revealed that 95% of transects drawn for the eastern zone underwent accretion (i.e., land reclamation) with a mean rate of 14 m/year indicating that the eastern zone faced rapid shoreline progression, with the highest rates due to the development of coastal areas for urban settlement. Similarly, 74% of transects drawn for the western zone experienced erosion (i.e., land loss) with a mean rate of −1.15 m/year indicating the weathering and erosion of rocky and sandy beaches by marine erosion. Among the 25 km length of the eastern zone, 94% (23.5 km) of the shoreline was found to be highly vulnerable, while the western zone showed much more stable conditions due to anthropogenic inactivity. Seasonal hydrodynamic analysis revealed approximately a 3% increase in the average wave height during the summer monsoon season and a 1% increase for the winter monsoon season during the post-land reclamation era. Coastal protection and management along the Sindh coastal zone should be adopted to defend against natural wave erosion and the government must take measures to stop illegal sea encroachments.

scholarly journals Coastal wetlands in Lianyungang, Jiangsu Province, China: probably the most important site globally for the Asian Dowitcher (Limnodromus semipalmatus)

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ziyou Yang ◽  
Jing Li ◽  
Yongxiang Han ◽  
Chris J. Hassell ◽  
Kar-Sin Katherine Leung ◽  
...  
Keyword(s):  
Coastal Wetlands ◽  
Coastal Wetland ◽  
Migratory Bird ◽  
Jiangsu Province ◽  
Bohai Bay ◽  
High Concentration ◽  
Human Disturbances ◽  
Stopover Site ◽  
Stochastic Events ◽  
Global Population

Abstract Background Despite an increasing number of surveys and a growing interest in birdwatching, the population and distribution of Asian Dowitcher (Limnodromus semipalmatus), a species endemic to the East Asian–Australasian and Central Asian Flyways, remains poorly understood, and published information about the species is largely outdated. In boreal spring 2019, over 22,432 Asian Dowitchers were recorded in a coastal wetland at Lianyungang, Jiangsu Province, China, constituting 97.5% of its estimated global population. Methods In 2019 and 2020, we conducted field surveys at Lianyungang to determine the numbers of Asian Dowitchers using the area during both southward and northward migrations. We also assessed the distribution and abundance of Asian Dowitchers elsewhere along the China coast by searching literature and consulting expert opinion. Results The coastal wetlands of Lianyungang are the most important stopover site for Asian Dowitchers during both northward and southward migrations; they supported over 90% of the estimated global population during northward migration in two consecutive years (May 2019 and 2020). This area also supported at least 15.83% and 28.42% (or 30.74% and 53.51% using modelled estimates) of the global population during southward migration in 2019 and 2020 respectively. Coastal wetlands in the west and north of Bohai Bay also have been important stopover sites for the species since the 1990s. Although comprehensive, long-term monitoring data are lacking, available evidence suggests that the population of the species may have declined. Conclusions The high concentration of Asian Dowitchers at Lianyungang during migration means the species is highly susceptible to human disturbances and natural stochastic events. The coastal wetlands of Lianyungang should be protected and potentially qualify for inclusion in China’s forthcoming nomination for World Heritage listing of Migratory Bird Sanctuaries along the Coast of Yellow Sea-Bohai Gulf of China (Phase II) in 2023. Additional research is needed to understand Asian Dowitchers’ distribution and ecology, as well as why such a high proportion of their population rely on the Lianyungang coast.

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