Wetland Shrinkage Research Articles

Spatiotemporal variations of groundwater and gully impact in two peatland watersheds in the Upper Yellow River, Qinghai‐Tibet Plateau

AbstractThe spatiotemporal variability of groundwater level is an important property of peatland hydrology that directly alternates water storage. Nonetheless, the current understanding of the variations of groundwater level over long periods of time remains limited. In this study, we investigated two peatland watersheds (0.151 km2 for Watershed 1 and 0.844 km2 for Watershed 2) in the Zoige Basin in the upper watershed of the Yellow River to monitor temporal variability of groundwater level using self‐recorded water loggers over 4 years (2017–2021). The main results demonstrate that (1) groundwater level variations were controlled by gully drainage in sites adjacent to the gully but were more affected by rainfall in sites distant from the gully. The groundwater level near the gully downcut was lower than that near the gully without complete downcutting through the pear layer, with a maximum difference of 58.3 cm, indicating the longitudinal effect of groundwater level in the watershed. (2) Because the rainfall had a lag effect on the groundwater level, the length of lag gradually decreased with increased rainfall intensity (i.e., the lag time for sites distant from the gully was about 18 min shorter than that of sites close to the gully in Watershed 1). (3) The peak values of the groundwater level occurred simultaneously with the maximum and minimum rainfall in Watershed 2, and the peak occurrence time was related to the ratio of precipitation to evaporation. In the downstream sites, the groundwater level fluctuated more than the upstream ones in Watershed 2. Moreover, the average groundwater level in the upstream sites was 14.3 cm higher than that of the middle ones, indicating a decreasing trend of water storage along the gully. (4) The differences in groundwater level between wet and dry seasons were clear, but the difference was smaller in the upstream sites due to limited gully incision and higher water storage within the peat layer. Additionally, groundwater level changes were more extreme on rainy days during both the wet and dry seasons, but the different intensities of rainfall resulted in stable groundwater in the dry season and an oscillating groundwater level in the wet season in Watershed 2. This study uncovers the groundwater dynamics in the two peatland watersheds, which is of great significance for understanding runoff variation, ecohydrological processes, and wetland shrinkage.

Anzali Wetland Crisis: Unraveling the Decline of Iran's Ecological Gem

AbstractThe wetland loss rate in Iran is faster than the global average. Comprehending the shrinkage rate in Iranian wetlands and identifying the underlying drivers of these changes is essential for safeguarding their ecosystems' health and services. This study proposes a novel gray‐box modeling framework to quantify the effects of climate change and anthropogenic activities on the wetlands, by combining process‐based and machine learning models. The developed model is utilized to project the Anzali coastal wetland shrinkage by simulating the complex interaction between the meteorological, hydrological, anthropogenic and sea water level characteristics, and the changes in wetland water surface area. Our framework aggregates Soil and Water Assessment Tool model, the 12 General Circulation Models of the Coupled Model Intercomparison Project Phase 6, Landsat imagery, and the Long Short‐Term Memory model to project the shrinkage of the wetland till 2100. A comprehensive range of climate and Land Use/Cover change scenarios are analyzed. The results show that wetland will seasonally desiccate in 2058, mainly due to increasing air temperature, reduction in precipitation and inflow, excessive sediment loading to the wetland, and decline in the Caspian Sea level. For optimistic scenarios, where no changes in the Caspian Sea level is considered, the wetland will gradually diminish and become a seasonal waterbody by 2100. The outcomes of this study highlight that the Anzali wetland desiccation has profound implications for the regional‐scale ecological balance, ecosystem health and function, public health, and local economy. Robust environmental interventions and sustainable development strategies are urgently needed to mitigate the detrimental impacts of climate and anthropogenic drivers on the wetland.

The effect of urbanization on the shrinkage of wetlands in the Noida-Greater Noida region and its surrounding sub-urban areas

Increasing urbanization has an adverse effect on the wetlands of Gautam Buddh Nagar and its surrounding region, so the study aimed to understand the impact of urbanization on the wetlands and its surrounding region, Landsat satellite data was used for the change detection study. This study deals with the inventorisation of wetlands of size greater than 10 ha in Noida-Greater Noida region and its adjacent areas and assess the impact of urbanization on these wetlands. Land-Use/Land-Cover (LULC) maps were developed using GIS tools. Temporal data analysis detected a loss of 16.36% wetlands of size more than 10 ha since 2010 in the Gautam Buddha Nagar district. LULC analyses revealed the high impact of urbanization on 5 out of the 8 sites. LULC change also detected shrinkage of wetlands and alternations of land use in the catchment area of most of the wetlands. The findings of this study were then used to suggest management recommendations for the conservation of wetlands at a local scale.

An assessment of long-term and large-scale wetlands change dynamics in the Limpopo transboundary river basin using cloud-based Earth observation data

Significant progress has been made in monitoring and assessing the effects of land use and land cover (LULC) changes on wetland extent. However, our understanding of wetland within the transboundary basins has been limited by the scarcity of available data on their dynamic changes over time. This study aimed to address this gap by analyzing the long-term and large-scale spatio-temporal extent of wetland in the Limpopo transboundary river basin (LTRB) over a 20-year period (2000–2020). To achieve this, we utilized the Google Earth Engine (GEE) cloud-computing platform and various remotely sensed data. The study had two primary objectives; (1) to examine LULC changes over time using machine learning algorithms applied to multisource remotely sensed data in GEE, and (2) to assess the relationship between LULC changes and the extent of wetlands in the basin. A total of nine land cover classes were identified, including shrublands, croplands, bare-surface, wetlands, sparse vegetation, tree cover, built-up areas, and grasslands. Shrublands covered 76–82% of the LTRB. On the other hand, wetlands and sparse vegetation were the least dominant, with proportions ranging from 0.3 to 2%. The overall accuracy of the classification results was within acceptable ranges, ranging from 77 to 78%. The study further revealed a continuing decline in wetlands extent and sparse vegetation, with average rates of 19% and 44%, respectively. Conversely, shrublands, croplands, and tree cover showed an increase, with average rates of 0.4% and 12.4% respectively. A significant finding was the replacement of a substantial portion (40%) of wetland areas with built-up areas, indicating that urban expansion is a major driver of wetland shrinkage in the study area. These results provide valuable insights into the declining extent of wetlands in the LTRB. Such findings are crucial for environmental management efforts, as they provide information on which wetlands should be prioritized when implementing strategies to prevent the negative impacts of LULC changes on wetlands in the area. Therefore, contributing towards achieving sustainable development goals relating to freshwater ecosystems protection and management.

Dust in Western Iran: the emergence of new sources in response to shrinking water bodies

We detected sources of dust in the Middle East that contribute to dust events in Western Iran in different seasons. By the analysis of the synoptic data, we identified 309 dusty days in Western Iran during the period 2000–2016. A dusty day is diagnosed if under low horizontal visibility (< 1 km), the dust in suspension is reported at least once a day in at least three synoptic stations. We identified dust sources in the Middle East based on the analysis of the MOD04L2 data from MODIS, the backward HYSPLIT trajectory model, and synoptic conditions. The most influential sources affecting Western Iran are located on the shore and northwest of Lake Tharthar, Hour-al-Azim Marsh, the shore of Razzaza, Habbaniyah Lakes, and West Hammar Marsh, which contributed to 110, 79, 59, 56, and 51 dusty days, respectively. The fluctuation of the surface water area largely contributes to the variability of dusty days in Western Iran. Indeed, the peak dust activity in Western Iran was during the period 2008–2012 in response to the substantial shrinkage of the main water bodies in Iraq. The main sources of dust influencing Western Iran are located in northern and eastern Saudi Arabia in spring, Deir ez-Zur in Syria’s Aleppo and Raqqa in summer, and Syria’s Homs and Al-Hasakah in winter and spring. Sources of dust in Western Iraq and in most parts of entire Iraq have, respectively, led to the formation of summer and spring dust events in Western Iran. Decreased precipitation in the Middle East from autumn 2007 to 2012 and the occurrence of severe droughts have also contributed to the shrinkage of lakes and wetlands, as well as the reduced agricultural productivity in the Middle East, all of which contributed to the intensification of dust activity in Western Iran in recent decades.

Major Role of Natural Wetland Loss in the Decline of Wetland Habitat Quality—Spatio-Temporal Monitoring and Predictive Analysis

Land use change significantly affects habitat quality, and the long time series exploration of dynamic variations in wetland habitat quality is of great significance to wetland conservation and management practices. Jingxin Wetland is located in the lower reaches of the Tumen River Basin, an important ecological function area in China. In recent years, under the influence of human activities and climate change, Jingxin Wetland has faced the threat of degradation and reclamation. This study investigated the dynamic evolution of habitat quality in Jingxin Wetland based on the CA-Markov model and the InVEST model at a long time scale and analyzed the drivers of habitat quality changes. Furthermore, habitat statuses under different policy orientations were explored using a multi-scenario development model. The results show that the total area of Jingxin Wetland exhibited a shrinking trend from 1964 to 2019, the wetland landscape was more fragmented, and the loss of natural wetland (marsh wetland) was serious. Consequently, wetland habitat quality has declined. According to scenario analysis, the study area should firmly follow the ecological conservation route in the future, through which the encroachment of human activities on wetlands can be effectively reduced and habitat conditions can be effectively improved. Both natural and economic development scenarios would result in the shrinkage of wetlands, which will extend the trend of declining habitat quality. It is noteworthy that the loss of wetland can be effectively reduced by implementing ecological conservation policies, which would reduce the degradation of wetland habitat quality. The results of this study can provide valuable references for wetland ecological conservation and ecological management practices.

Evaluation of causes and effects of environmental shifts in the Lower Digaru River Basin, Assam, India

Environmental issues like deforestation, biodiversity loss, soil erosion, siltation, wetland shrinkage, river bank erosion, etc. in drainage basin perspectives today are in a rapid flux triggered by population growth and developmental activities. Focusing on the Lower Digaru River basin of North-East India,the present study investigates the changes in theLand Use / Land Cover (LULC)trend using geospatial techniques and the cause-effect relationship by identifying the various environmental issues operating within the study area. The study area has been classified into nine LULC classes: dense forest, openforest, scrub forest, fallow land, barren land, cropland, dense scrub, mixed built-up land, and water body. The results revealed that the area under dense forest has drastically declined from 60.25 % to 16.63 % during 1999-2020. In contrast, the other important categories like Mix built-up land (8.11 % to 14.05 %), scrub forest (2.1 % to 25.11 %), barren land (0.2 % to 6.63 %) and open forest (11.9 % to 18.34 %) show an increasing trend of change during the said period. Post-classification comparison of the classified images based on the transition matrix indicated that approximately 40 % of the total area under forest had been converted to scrub forest, followed by 25.09 % to open forest and, most significantly, 5.22 % to mix built-up land during 1999 -2020. Increasing population pressure and growth of economic activities like the establishment of brick industries, coke industries, and sand mining were the major driving forces for such LULC changes. Environmental implications like wetland shrinkage, river bank erosion, alteration of human occupation and economy, etc., were the study area’s prime concern. The findings suggest that integrated watershed management and land use planning should be implemented in the Lower Digaru River Basin.

Investigation on the Status Quo of Ecological Environment Construction in Northeast China from the Perspective of Dual Carbon Goals.

Since the 20th century, the resources and environment in Northeast China have changed, and it is one of the typical regions that have short-term or high-intensity environmental impacts in the world. However, due to the excessive consumption of regional resources and strong environmental pollution to the atmospheric environment, development is being greatly affected. Maintaining the natural ecological environment has become a very urgent task. This paper studies the important ecological environment problems in Northeast China from the perspective of double carbon goals. The study points out that there are ecological problems in Northeast China, such as the lack of forest resources, the aggravation of desertification, the decline of black soil quality, and the shrinkage of wetlands, which are severe urban environmental protection problems. At the same time, affected by the trend of world environmental change, policy drivers in Northeast China, and some relatively new environmental pollution problems, the natural environmental quality of Northeast China will still have a significant decline in the future. The future development of Northeast China will be based on the perspective of double carbon goals, constantly improve the ecological environment monitoring system, strengthen the research of scientific and technological system, strengthen innovation, and vigorously develop circular economy and further improve the construction of basic systems. Through a series of ecological environment governance and the coordinated development of economy and ecological environment, the dual growth of economy and ecological environment in Northeast China will be realized, and the overall revitalization of the old industrial zone in Northeast China will be realized.

Research status of heavy metal pollution evaluation in urban wetlands in China

Urban wetlands are one of the ecosystems most closely related to human production and life, and have various functions such as stabilizing the environment, improving the urban environment, regulating and storing floodwater, supplementing groundwater, recreation, science and education culture, and protecting biodiversity. With the continuous shrinkage of urban wetlands in recent years and frequent pollution, many scholars at home and abroad have carried out a lot of research work on urban wetlands, of which the evaluation of heavy metal pollution in urban wetlands is one of the priorities. In this paper, this paper analyzes the reports on heavy metal pollution in urban wetlands in China in recent years, reviews the current situation of pollution evaluation in sediment, soil and water bodies of urban wetlands, and summarizes and summarizes the pollution evaluation methods of heavy metals. Among the many evaluation methods, the single index method, the ground accumulation index method, the potential ecological risk assessment method and the water quality standard level method are the most used.

Comparing the Yangtze and Mississippi River Deltas in the light of coupled natural-human dynamics: Lessons learned and implications for management

The Yangtze River Delta (YRD) and Mississippi River Delta (MRD) are two of the largest deltas in the world. Despite similar forcing conditions of fluvial sediment reduction and relative sea-level rise, there are significant differences in deltaic change caused by hydrodynamics and human activities. In this review, we compare the morphological changes of the two deltas at multiple spatial and temporal scales and identify the lessons learned from past engineering and management strategies. While the YRD has seen an increase of subaerial land of ~1500 km2 since 1950, the MRD has lost approximately 5000 km2 of land since the early 1930s. Extensive land reclamation and coastal shoreline embankment in the YRD have led to land gain at the expense of tidal wetland shrinkage. In contrast, flood control, waterway transportation, and petroleum industry in the MRD have resulted in levee construction and canal building, which together with subsidence and sea-level rise, have led to significant wetland loss in the MRD. The tidal forcing in the YRD is much stronger than that in the MRD, which has played a role in redistributing subaqueous sediment back into the delta plain, offsetting the negative effect of fluvial sediment reduction. In contrast with continuous population increase on the YRD, wetland loss and exposure to flooding hazards have resulted in population loss on the MRD. These comparative analyses reveal that nature and human interventions have acted together in shaping the modern deltaic morphology. Using the Driver-Pressure-State-Impact-Response (DPSIR) analysis framework, we propose a conceptual model to provide holistic understanding of the natural-human coupled delta system and management strategies, which could yield broad implications for coping with the future challenges in global deltas.

Impacts of land use change on ecosystem service value based on SDGs report--Taking Guangxi as an example

Ecosystem services provide a variety of benefits for mankind, and their sustainable use plays an important role in achieving the Sustainable Development Goals (SDGs). This study takes Guangxi as the research object and compares multiple intelligent classification algorithms for land cover based on multi-source data. Selects Random Forest (RF) classification algorithms for land cover classification, analyses their temporal and spatial changes, and the extracted results produce SDG 15.1.1, 15.1.2, 15.1.4 indicators, and assess the degree of completion of Guangxi’s SDGs 15.2 indicators. On this basis, the equivalent factor method was used to evaluate the change of ecosystem value caused by land use change, and the direct impact of land use change on SDG15.9 was evaluated. The results indicate that:(1) From 1990 to 2020, forest was the most important land use mode in Guangxi, and the most serious wetland shrinkage was in Beihai and Nanning; The overall trend of land use changes is that wetlands, forests, and grasslands have decreased, dry land and construction land have increased, and bare land has remained basically remained unchanged. (2) From 1990 to 2020, the SDG 15.1.1 indicator showed a slow rise and then a rapid decline. The SDG 15.1.2 indicator showed a continuous downward trend. The SDG 15.1.4 indicator showed a steady upward trend. Guangxi failed to achieve the target of SDG15.2 by 2020. (3) From 1990 to 2020, the overall ecosystem service value in Guangxi showed a decreasing trend, and the one-way ecosystem service value in Guangxi was dominated by hydrological regulation and climate regulation. The ecosystem service value showed a spatial pattern of “low in the central region and high in the surrounding areas.” (4) Grassland to forest and dryland to forest were the main types of ecological service income; Forest conversion to dryland is the most important type of ecological service loss. (5) As a whole, only dryland sensitivity index less than 0 during 2010–2015 had a negative impact on Ecosystem services values (ESV), while other time and land use type sensitivity index were all greater than 0 had a positive impact on ESV.

Soil particle and moisture-related factors determine landward distribution of bacterial communities in a lateral riverside continuum of the Xilin River Basin

Continuous landscape components along the lateral riverside are affected by both hydrologic connectivity and disconnectivity. In recent years, anthropogenic activities and climate changes have caused wetland shrinkage and land degradation along the lateral riverside of many arid and semiarid regions. Since microorganisms are major drivers of soil biochemical cycling, it is essential to examine soil microbial communities along the lateral landscape continuum to understand their ecosystem functioning and predict future land changes. Here, we collected samples along a lateral riverbed center-riverbed edge-oxbow lake-floodplain-terrace continuum (i.e., landward distribution) in the Xilin River Basin, Inner Mongolia, China. The floodplain had the highest microbial diversity and heterogeneity, with Bacteroidetes, β- and γ-Proteobacteria being the most abundant taxa. In contrast, the terrace had the lowest microbial diversity and heterogeneity, with Acidobacteria, Actinobacteria, Verrucomicrobia, Gemmatimonadetes, and α-Proteobacteria as the most abundant taxa. Silt particle, salinity, and moisture were the most influential factors for landward variation of bacterial communities along the riverside continuum. Altogether, we demonstrate that dominant bacterial lineages, soil particles, and moisture-related factors are valuable indicators of this continuum, which can be leveraged for the early prediction of drought-induced wetland shrinkage and grassland desertification.

Overview of recent land cover changes, forest harvest areas, and soil erosion trends in Nordic countries

Mapping spatiotemporal land cover changes offers opportunities to better understand trends and drivers of environmental change and helps to identify more sustainable land management strategies. This study investigates the spatiotemporal patterns of changes in land covers, forest harvest areas and soil erosion rates in Nordic countries, namely Norway, Sweden, Finland, and Denmark. This region is highly sensitive to environmental changes, as it is experiencing high levels of human pressure and among the highest rates of global warming. An analysis that uses consistent land cover dataset to quantify and compares the recent spatiotemporal changes in land cover in the Nordic countries is missing. The recent products issued by the European Space Agency and the Copernicus Climate Change Service framework provide the possibility to investigate the historical land cover changes from 1992 to 2018 at 300 m resolution. These maps are then integrated with time series of forest harvest areas between 2004 and 2018 to study if and how forest management is represented in land cover products, and with soil erosion data to explore status and recent trends in agricultural land. Land cover changes typically involved from 4% to 9% of the total area in each country. Wetland showed the strongest reduction (11,003 km2, −11% of the wetland area in 1992), followed by forest (8,607 km2, −1%) and sparse vegetation (5,695 km2, −7%), while agriculture (15,884 km2, 16%) and settlement (3,582 km2, 84%) showed net increases. Wetland shrinkage dominated land cover changes in Norway (5,870 km2, −18%), followed by forest and grassland with a net gain of 3,441 km2 (3%) and 3, 435 km2 (10%), respectively. In Sweden, forest areas decreased 13,008 km2 (−4%), mainly due to agriculture expansion (9,211 km2, 29%). In Finland, agricultural areas increased by 5,982 km2 (24%), and wetland decreased by 6,698 km2 (−22%). Settlement had the largest net growth in Denmark (717 km2, 70%), mainly from conversion of agriculture land. Soil erosion rates in Nordic countries are lower than the global average, but they are exacerbating in several locations (especially western Norway). The integration of the land cover datasets with maps of forest harvest areas shows that the majority of the losses in forest cover due to forestry operations are largely undetected, but a non-negligible share of the forest-to-agriculture (up to 19%) or forest-to-grassland (up to 51%) transitions overlap with the harvested sites. Forestry activity in the study region primarily involves small-scale harvest events that are difficult to be detected at the 300 m resolution of the land cover dataset. An accurate representation of forest management remains a challenge for global datasets of land cover time series, and more interdisciplinary international efforts are needed to address this gap. Overall, this analysis provides a detailed overview of recent changes in land cover and forest management in Nordic countries as represented by state-of-the-art global datasets, and offers insights to future studies aiming to improve these data or apply them in land surface models, climate models, landscape ecology, or other applications.

Tracking changes in aquaculture ponds on the China coast using 30 years of Landsat images

Although coastal aquaculture ponds provide high-quality fish protein for billions of people, they are threatened by urbanization, pollution, and climate change. Moreover, colossal aquaculture ponds pose damages such as natural wetland shrinkage and water quality deterioration. However, understanding the trends and drivers of coastal aquaculture ponds on a national scale remains a challenge. In this study, a decision-tree classifier was used to quantify the spatiotemporal distribution of aquaculture ponds over last 30 years in 12 provinces located on the coast of China. Moreover, we analyzed their trends and drivers, including geographical conditions, socioeconomic factors, and development policies. The key results of the study include the following: (1) from 1990 to 2020, the cumulative area and holding area of aquaculture ponds reached 21997.90 km2 and 9613.66 km2, representing 3.7-fold and 1.6-fold increase, respectively, than the 1990 values. Based on geographical conditions, most aquaculture ponds tend to be located in coastal plains and bays following the distribution of low-lying land. (2) Influenced by different levels of socioeconomic development and changed policies, the holding area of aquaculture ponds experienced a “rapidly increasing period” from 1990 to 2011, growing by 246 km2 per year; “stable period” between 2011 and 2017; and “sharply shrinking period” after 2017 declining by 417 km2/year. (3) Coastal land reclamation played a critical role in the expansion of aquaculture ponds by cumulatively contributing approximately 22% of the land resource in the past 30 years. In the future, as a result of increasing land competition, the extent of aquaculture ponds on the China coast tends to decrease continually.

北方寒冷干旱地区内陆湖泊生态安全评价指标体系研究——以呼伦湖为例

呼伦湖作为我国北方寒冷干旱地区内陆湖泊的典型代表，在涵养水源、调节气候、防风固沙及维系呼伦贝尔草原生态系统平衡乃至我国北方生态安全屏障等方面发挥着不可替代的作用。准确识别呼伦湖流域主要生态安全问题、完善其生态安全评价指标体系对于科学研判呼伦湖生态环境状况、维持区域可持续发展及精准实施底线管控政策具有重要意义。在遥感影像、地面调查、实验模拟等多尺度数据分析基础上，结合历史资料收集、专家咨询、部门访谈等方式分析识别了呼伦湖区域生态安全问题及成因：（1）气候暖干化及超载放牧等因素使得草地退化显著，土地沙化、盐碱化面积扩大；（2）草原退化增加了干草入湖、大气干湿沉降及水土流失等水环境污染负荷；（3）气候暖干化造成湿地萎缩，加之长期的过度捕捞等人类活动使得渔业资源枯竭、鱼类小型化特征显著，水生生态系统稳定性下降，蓝藻水华频发。在全面诊断分析区域生态安全问题的基础上，以山水林田湖草系统方法论为理论指导，以改善呼伦湖流域生态环境质量为核心目标，依据评价指标的针对性、科学性、可操作性及系统性原则，采用压力-状态-响应（Pressure-State-Response，PSR）模型，以气象条件、人口、水资源、水环境压力及人类活动等5个一级指标构成的压力子系统，以水环境状况、水生态状况、陆域生态状况、生态系统服务功能和敏感性、景观格局及生态风险等6个指标构成的状态子系统，以生态治理措施及生态治理投入等2个指标构成的响应子系统，共同组成了一套包含13个一级指标38个二级指标的天空地一体、陆湖统筹的生态安全评价指标体系，以期为呼伦湖及北方寒冷干旱区类似湖泊的生态安全评价研究提供借鉴。;Hulun Lake, as a typical representative of inland lakes in the cold and arid areas of northern China, plays an irreplaceable role in water conservation, climate regulation, windbreak, and sand fixation. This lake maintains balance in the Hulun Buir grassland ecosystem and even the ecological-security barrier of northern China. Thus, identifying the main ecological-security problems in Hulun Lake Basin and improving its ecological-security evaluation index system are highly significant. The obtained data can be used for the scientific research and assessment of the ecological environment status of Hulun Lake, the maintenance of regional sustainable development, and the accurate implementation of bottom-line management and control policy.Based on remote-sensing imagery, ground survey, experimental simulation, and other multi-scale data analyses, this paper aims to analyze and identify the ecological-security problems of Hulun Lake area and their causes by combining historical data collection, expert consultation, and department interview. The results are as follows:(1) warm and dry climate, overgrazing, and other factors induce significant grassland degeneration, so land desertification and salinization area expand. (2) grassland degradation increases water-pollution load, such as hay into lake, atmospheric dry and wet settlement, and soil erosion. (3) climate warming and drying cause wetland shrinkage. Long-term overfishing and other human activities lead to the depletion of fishery resources and significant fish miniaturization. Consequently, the stability of aquatic ecosystem is reduced, and blue-green algal blooms occur frequently. Based on the comprehensive diagnosis and analysis of regional ecological-security problems, together with theoretical guidance by the methodology of mountains, rivers, forests, fields, lakes, and grass-system methodology, and improving the ecological environment quality of Hulun Lake basin as the core goal, the pressure-state-response (PSR) model is adopted in the present study according to the principles of focalization, scientific nature, operability, and systematicness of evaluation indices. The pressure subsystem comprises five first-class indicators, namely, meteorological conditions, population, water resources, water environment pressure, and human activities. The state subsystem comprises six indicators, namely, water environment, water ecology, land ecosystem, ecosystem service function and sensitivity, landscape pattern, and ecological risk. The response subsystem comprises two indicators, namely, ecological-management measures and ecological-management investment. Then, they jointly form an ecological-security evaluation index system with the integration of sky and land and the overall planning of land and lake, which includes 13 first-class indicators and 38 second-class indicators, to serve as a reference for studying the ecological-security evaluation of Hulun Lake and similar lakes in cold and arid areas.

Changes of groundwater flow field of Luanhe River Delta under the human activities and its impact on the ecological environment in the past 30 years

The Luanhe River Delta is located in the center of the Circum-Bohai Sea Economic Zone. It enjoys rapid economic and social development while suffering relatively water scarcity. The overexploitation of groundwater in the Luanhe River Delta in recent years has caused the continuous drop of groundwater level and serious environmental and geological problems. This study systematically analyzes the evolution characteristics of the population, economy, and groundwater exploitation in the Luanhe River Delta and summarizes the change patterns of the groundwater flow regime in different aquifers in the Luanhe River Delta according to previous water resource assessment data as well as the latest groundwater survey results. Through comparison of major source/sink terms and groundwater resources, the study reveals the impacts of human activities on the groundwater resources and ecological environment in the study area over the past 30 years from 1990 to 2020. The results are as follows. The average annual drop rate of shallow groundwater and the deep groundwater in the centers of depression cones is 0.4 m and 1.64 m, respectively in the Luanhe River Delta in the past 30 years. The depression cones of shallow and deep groundwater in the study area cover an area of 545.32 km2 and 548.79 km2, respectively, accounting for more than 10% of the total area of the Luanhe River Delta. Overexploitation of groundwater has further aggravated land subsidence. As a result, two large-scale subsidence centers have formed, with a maximum subsidence rate of up to 120 mm/a. The drop of groundwater level has induced some ecological problems in the Luanhe River Delta area, such as the zero flow and water quality deterioration of rivers and continuous shrinkage of natural wetlands and water. Meanwhile, the proportion of natural wetland area to the total wetland area has been decreased from 99% to 8% and the water area from 1776 km2 to 263 km2. These results will provide data for groundwater overexploitation control, land subsidence prevention, and ecological restoration in plains and provide services for water resources management and national land space planning.© 2021 China Geology Editorial Office.

Modeling Intersecting Processes of Wetland Shrinkage and Urban Expansion by a Time-Varying Methodology

Continuous urban expansion worldwide has resulted in significant wetland degradation and loss. A limited number of studies have addressed the coupling of wetland and urban dynamics, but this relationship remains unclear. In this study, a time-varying methodology of predicting wetland distribution was developed to support decision-making. The novelty of the methodology is its ability to dynamically simulate wetland shrinkage together with urban expansion and reveal conflicts and potential tradeoffs under different scenarios. The developed methodology consists of three modules: a historical change detection of wetland and urban areas module, a spatial urban sprawl simulation and forecasting module that can accommodate different development priorities, and a wetland distribution module with time-varying logistic regression. The methodology was applied and tested in the Tonghu Wetland as a case study. The wetland and urban extents presented a spatially intersecting shift, where wetlands lost more than 40% of their area from 1977 to 2017, while urban areas expanded by 10-fold, threatening wetlands. The increase in the relative importance metric of the time-varying regression model indicated an enhanced influence of urban expansion on the wetland. An accuracy assessment validated a robust statistical result and a good visual fit between spatially distributed wetland occurrence probabilities and the actual distribution of wetland. Incorporating the new variable of urban expansion improved modeling performance and, particularly, realized a greater ability to predict potential wetland loss than provided by the traditional method. Future wetland loss probabilities were visualized under different scenarios. The historical trend scenario predicted continuously expanding urban growth and wetland shrinkage to 2030. However, a specific urban development strategy scenario was designed interactively to control the potential wetland loss. Consideration of such scenarios can facilitate identifying tradeoffs to support wetland conservation.

Adaptive co-management model for the East Kolkata wetlands: A sustainable solution to manage the rapid ecological transformation of a peri-urban landscape

Human-induced land use changes like agriculture and urban development occur commonly at the cost of natural wetlands, which require immediate attention and sustained efforts from urban planners and concerned governments. In view of the East Kolkata Wetlands (EKW), India, this paper has examined the trend, causes, extent and impacts of landscape transformation during the last few decades. Hence we aim to present a review of several studies in and around EKW and suggests a sustainable model for EKW. This ‘Ramsar site of International Importance’ is one of the world's largest wastewater-fed aquaculture systems where the city sewage is recycled for pisciculture and agriculture, and acts as flood resistance for the city of Kolkata. Rapid encroachment in the EKW due to unplanned development has caused various environmental, social and economic impacts. The key ecological impacts found in the study included loss of faunal and floral diversity, eco-toxicological impacts, etc. In terms of biodiversity loss, while the number of bird species in the EKW decreased from 248 in 1960s to 72 in 2005, about 59% fish species are near threats, vulnerable and endangered. Reported persistent organic pollutants (POPs) around the EKW region were found to pose deleterious impact on environment and ambient biota. Several studies have evidenced that the open burning of solid waste in the dumping ground of Dhapa is a potential source of polychlorinated biphenyls (PCBs) and polychlorinated dibenzo dioxin/furans (PCDD/Fs). Further the ecological transformation of the EKW focussing on policy development and regulatory compliance issues has been studied in this paper. The aspects of encroachment and wetland shrinkage triggered by economic drivers like urban sprawl have been analyzed. The paper presents adaptive co-management as the future roadmap for action to curb further degradation of the wetlands, and adopt an integrated approach of environmental, political, physical, economic and institutional aspects. It is envisaged that the adaptive co-management model will contribute to long-term sustainable sustenance of this precious ecosystem.

Remote Observation in Habitat Suitability Changes for Waterbirds in the West Songnen Plain, China

Being one of the most important habitats for waterbirds, China’s West Songnen Plain has experienced substantial damage to its ecosystem, especially the loss and degradation of wetlands and grasslands due to anthropogenic disturbances and climate change. These occurrences have led to an obvious decrease in waterbird species and overall population size. Periodic and timely monitoring of changes in habitat suitability and understanding the potential driving factors for waterbirds are essential for maintaining regional ecological security. In this study, land cover changes from 2000 to 2015 in this eco-sensitive plain were examined using Landsat images and an object-based classification method. Four groups of environmental factors, including human disturbance, water situation, food availability, and shelter safety, characterized by remote sensing data were selected to develop a habitat suitability index (HSI) for assessing habitat suitability for waterbirds. HSI was further classified into four grades (optimum, good, general, and poor), and their spatiotemporal patterns were documented from 2000 to 2015. Our results revealed that cropland expansion and wetland shrinkage were the dominant land cover changes. Waterbird habitat areas in the optimum grade experienced a sharp decline by 7195 km2. The habitat area in good suitability experienced reduction at a change rate of −8.64%, from 38,672 km2 to 35,331 km2. In addition, waterbird habitats in the general and poor grades increased overall by 10.31%. More specifically, the total habitat areas with optimum suitable grade, in five national nature reserves over the study region, decreased by 12.21%, while habitat areas with poor suitable grade increased by 3.89%. Changes in habitat suitability could be largely attributed to the increase in human disturbance, including agricultural cultivation from wetlands and grasslands and the expansion of built-up lands. Our findings indicate that additional attention should be directed towards reducing human impact on habitat suitability for sustainable ecosystems.

Influence of geomorphic and anthropogenic activities on channel morphology of River Jhelum in Kashmir Valley, NW Himalayas

The Srinagar reach of the River Jhelum in Kashmir Valley, India exhibits complex meandering and variable width (47–180m) and depth (0.76–6.09m). The reach is characterised by sharp bends in the river course, channel sinuosity, linearity of meander bends, linear truncation of braid-bars, and concavities and convexities in the river channel reflecting varied river geomorphic processes. During the extreme hydrological event of September 2014, a large number of river breaches occurred along the river Jhelum, particularly in the Srinagar stretch of the river, due to the floodwaters overflowing the banks and the consequent bank erosion. The flooding situation was aggravated over the years by anthropogenic influences like the extensive urbanization of the Jhelum floodplains, encroachment of river banks and siltation of water courses due to the deforestation in the catchment and the shrinkage of wetlands which usually act as sponge during the flooding events. To establish a relationship between the geomorphic processes and anthropogenic activities on river morphology, we used various geomorphic parameters and techniques like river profiling, bathymetric profiling, lateral entrenchment ratio, water velocity, sinuosity index, supported by GPS and other field measurements. The impact of the geomorphic and human induced changes on the channel morphology was corroborated with the data from the river breaches that occurred during the 2014 flooding, a few of which occurred at the locations where geological structures (lineaments/faults) cut across the river banks. Based on the investigations from this study, it is suggested that varied geomorphic processes and the unchecked anthropogenic activities in the vicinity and catchment have significantly impacted the channel morphology of the river Jhelum in Kashmir Valley increasing the vulnerability of the Srinagar city to flooding.