Wetland Characteristics Research Articles

Dynamics Analysis of Spatial Distribution and Landscape Pattern of Wetlands in the Weihe River Basin from 1980 to 2020

The wetland ecosystem is one of the most important carbon sinks on Earth, the most biodiverse ecological landscape in nature, and one of the most important living environments for human beings. The Weihe River wetland is located in the Guanzhong Plain urban agglomeration, with extreme climate and urban expansion having a great impact on its dynamic changes. Revealing the characteristics of and trends in wetland dynamics in the Weihe River Basin is the key to protecting and maintaining the healthy development of the Weihe River wetlands. This paper analyzed the changing characteristics of land use types and landscape patterns in the wetlands of the Weihe River Basin using wetland land use data from six periods in the Weihe River wetland from 1980 to 2020 and explored the spatial and temporal distribution characteristics and dynamic changes in wetlands in the Weihe River Basin. The results showed the following: (1) Wetlands in the Weihe River Basin, dominated by rivers, saw area fluctuations with an initial decline followed by an increase. Land use changes followed a slow–fast–slow trend. (2) From 1980 to 2020, frequent conversions among wetland types were observed. The primary transformation was the conversion of marshes into lakes (18.05 km2) and reservoirs/ponds (17.98 km2). Approximately 0.06 km2 of lakes were transformed into canals/channels. (3) River patches have the largest area, while canals/channels have the smallest. The patch density (PD) and landscape shape index (LSI) of wetlands fluctuate significantly, and the reduction in area leads to a 3.46% decrease in aggregation index (AI). Shannon’s diversity index (SHDI) has decreased by 5.41%. (4) The centroid of marshes experiences significant changes, while river changes are complex. The centroid changes in reservoirs/ponds are located along the southeast–northwest line. Canals/watercourses remain stable. Lakes exhibit the longest migration. This study provides robust scientific support for wetland ecological protection, policy formulation, and social sustainable development by conducting an in-depth analysis of the dynamic change characteristics of wetlands in the Weihe River Basin.

Distribution and Long-Term Variation of Wetland Land Cover Types in the Yellow River Delta Remote Sensing Monitoring

Wetlands are dubbed the “kidneys of the earth” and are involved in climate regulation, carbon sequestration, ecological balance preservation, and reducing the surface water pollution. Ongoing economic development has introduced pressing challenges to wetland environments. In this context, extracting coastal wetland information and monitoring the dynamic changes are essential. Using long-term sequence Sentinel-2 satellite remote sensing images and field observations, this research proposed a Dynamic Bayesian Network classification model framework based on conjugate gradient updates. We compared the wetland feature extraction effects of the Fletcher–Reeves and the Polak–Ribière–Polyak algorithms of the conjugate gradient. Then, remote sensing combined with the FRDBN classification model was used to extract the information pertinent to wetland feature types and changes in wetland areas and analyze alterations in the distribution characteristics of land cover types. The results showed that the FRDBN model achieved high accuracy (above 96%), and kappa coefficients exceeded 0.96. Long-term monitoring revealed that the area of wetlands increased by 0.85 × 104 hm2 from 2016 to 2021. Non-aquatic land cover types exhibited pronounced dynamic changes, with the area of change representing 58–69% of the monitored total. Specifically, the transition between salt marsh vegetation and artificial wetlands was relatively obvious. The FRDBN model provides a new method for extracting wetland feature information. Wetland protection, dynamic monitoring, and carbon sink research can provide robust technology support, facilitating investigations into coastal salt marsh carbon sinks and technological advances in carbon sink assessment.

Multi-Scale Gross Ecosystem Product (GEP) Valuation for Wetland Ecosystems: A Case Study of Lishui City

Traditional gross ecosystem product (GEP) accounting methods often operate at macro scales, failing to reflect the localized and nuanced values of wetland ecosystems. This study addresses these challenges by introducing a fine-grained classification system based on a localized adaptation of international standards. The framework integrates high-precision national land surveys and remote sensing quantitative analysis while incorporating fisheries resource models, climate regulation beneficiary mapping, and visitor interpolation to address data scarcity related to human activities. This approach refines the spatial calculation methods for functional quantity accounting at fine scales. The results demonstrate that the refined classification maintains consistency with traditional methods in total value while adapting to multi-scale accounting, filling gaps at small and medium scales and providing a more accurate representation of localized wetland characteristics. Additionally, the study highlights the dominance of cultural services in GEP, emphasizing the need to balance cultural and regulatory services to ensure fairness in decision-making. Finally, a village-scale decision-support model is proposed, offering actionable guidance for wetland management and sustainable development planning.

Integrating Wetlands as Nature-Based Solutions for Sustainable Built Environments

Wetlands are ecosystems that can provide numerous services critical for sustainable development, especially in urban areas, by ensuring environmental stability. The wetlands receive increasing recognition as Nature-Based Solutions (NBSs) to environmental challenges. This review synthesizes the numerous roles of wetlands as NBSs for promoting sustainability in both rural and urban environments and highlights the potential contributions of multiple wetland services and benefits towards sustainable built environments. The review methodology involved an article search from various databases with the utilization of specific keywords in an organized framework to understand the contribution of wetlands as NBSs. The articles were reviewed to provide a comprehensive analysis of the existing research on the associated topics, focusing on specific sub titles and pre-selected themes. The findings of this review identify various parameters through which wetlands contribute to sustainable built environments, including ecological resilience, storm water management, climate adaptation, biodiversity enhancement, recreational opportunities, pollution control, and cultural values. The review also encompasses case studies of different types of wetland features such as riparian buffer zones, retention ponds, reed beds, bio swales, rain gardens, constructed wetlands, etc. in the urban environment and their contribution as NBSs. These contributions are discussed in terms of integration in urban development planning in different segments. Future work recommendations consist of a holistic integration of wetlands into urban planning and design considerations to promote more resilient, healthy, and sustainable built environments for present and future generations.

Hydrogeomorphic conditions drive aquatic macroinvertebrate diversity between depression and slope wetlands in a mountainous region

Aquatic macroinvertebrates inhabiting freshwater wetlands make important contributions to biodiversity. However, environmental characteristics of wetlands is often varied in a specific region, especially in mountainous areas. We investigated 24 depression wetlands and 20 slope wetlands in the Great Xing'an Mountains in Northeast China and aimed to reveal the hydrogeomorphic settings in driving the wetland aquatic macroinvertebrate diversity and offer insights to environmental management. We found that depression wetlands supported higher taxonomic richness and more habitat specialists. Fifteen orders or infraclasses responded positively to depression wetlands, whereas eight orders responded positively to slope wetlands. The composition of aquatic macroinvertebrate assemblages differed significantly between the depression and slope wetlands. Additionally, the variation in species composition in the depression and slope wetlands are largely explained by habitat variables. For community assembly of aquatic macroinvertebrates, both wetland types were largely driven by stochastic processes, with a higher proportion observed in the slope wetlands. Whereas a significant distance-decay relationship and stronger dispersal limitation were detected in the depression wetlands. These findings enhance our understanding of diversity patterns and mechanisms driving aquatic macroinvertebrate community assembly in mountain wetlands. Our research also highlighted the critical need to attach importance to hydrogeomorphic settings and habitat variables in driving aquatic macroinvertebrate diversity for more effective wetland management and conservation.

Dynamic Change Characteristics of Wetlands in Hefei and their Driving Factors Along the Urban–Rural Gradient

Wetlands, as vital components of urban ecological infrastructure, provide essential ecosystem services. However, they face increasing risks of degradation and loss due to their vulnerability, environmental changes, and human activities. Therefore, effective restoration efforts are urgently needed. This study adopts a novel approach by considering the urban–rural gradient and integrates land use data, ecological parameters, and anthropogenic factors in Hefei City. Through morphological spatial pattern analysis, principal component analysis, and affinity propagation, this study identifies and analyzes urban–rural gradients. Using the optimal parameter geographic detector, the drivers of wetland changes from 1990 to 2020 are quantitatively assessed across different urban–rural gradients in Hefei. The findings indicate the following. (1) A persistent reduction in wetland expanse throughout the study duration, diminishing from 1274.56 km2 in 1990 to 1119.37 km2 in 2020, constituting a decrement of 12.17%. (2) Based on geographic detector outcomes, disparate driving forces underpin wetland dynamics across urban–rural gradients, with urban locales predominantly influenced by organic carbon and the proportion of impervious surface factors. Meanwhile, in agricultural and semi-ecological villages, silt is the primary factor, while ecological villages are primarily modulated by both silt and gross domestic product factors. Additionally, synergistic interactions manifest heightened explanatory power. This study elucidates the mechanistic underpinnings of wetland dynamics along urban–rural gradients, providing pivotal insights for developing targeted wetland restoration and conservation policies pertinent to the urban–rural developmental trajectory in Hefei City. Concurrently, it offers relevant recommendations for the multifaceted stewardship and sustainable development of wetlands in Hefei City in the foreseeable future.

The Breeding colonies, population growth and breeding success of the Dalmatian pelican Pelecanus crispus in Greece: a country-wide perspective, 1967-2021

Greece holds the third larger breeding population of Dalmatian Pelican in the world. We present data about the establishment and growth, breeding performance and conservation status for all six colonies of the species in Greece for 40 years. Main features of wetlands and colonies are described. We discuss the local, regional and global natural and anthropogenic factors that may have affected colony growth. After 1982 colony surveys were carried out with various methods, adapted to the particularities of each wetland and availability of resources, and targeted estimating number of nests and number of near-fledged young via direct counting either during on-site visits or from vantage points, and recently, counts on photos taken by drones flown one or more times during breeding. Number of nests in Lake Mikri Prespa rose from ca. 100 to 1200-1500 and levelled-off. DPs from Prespa started breeding successfully in Kerkini in 2004 after placement of artificial nesting rafts. The Karla Reservoir was colonised in 2011, just two years after it started filling with water. The DP colony on Lake Chimaditis, an important stop over and feeding site, probably initiated around 2016 and continues growing. The two colonies at the western coastline have limited exchanges with those in the eastern part of the country. Amvrakikos increased and levelled off recently as conservation and management measures restricted disturbance, whilst emigrants re-established the old colony at Messolonghi in 2011 which continues to grow. The overall breeding population in Greece grew from ca 100 to over 2000 br pairs showing an annual growth rate of 7.9%. Younger colonies show high annual growth rates clearly attributed to immigration, while older colonies have growth rates less than 10%. Interacting natural and anthropogenic factors are assumed to have contributed to pelican increase in Greece the last 40 years: better legal protection status, increasingly effective protection, patrolling and conservation measures; public awareness campaigns; provision of artificial nesting structures; increased winter survival due to higher temperatures owed to climate change; less disturbance and persecution due to decline of fisheries; increasing abundance and availability of fish due to eutrophication and climate change; increasing numbers of sympatric great cormorants rendering pelican fishing more efficient; appearance of new wetlands and change of wetlands due to human intervention works.

Landscape context and wetland attributes influence wintering waterbirds in important bird and biodiversity areas: implications for conservation and management

ContextThe intensification and expansion of human activities have caused profound changes in global wetlands and their associated aquatic bird communities. Understanding the mechanisms that drive the spatial assemblages of wetland birds is important for the development of effective conservation and management strategies.ObjectivesThe overall objective was to evaluate the influence of wetland features such as size and distance to the nearest coastline, and landscape composition, configuration, and function in shaping waterbird richness and abundance in 43 Tunisian Important Bird and Biodiversity Areas (IBAs).MethodsSystematic waterbird surveys on species abundance and richness at each IBA were carried out between December and January in 2020/2021 and 2021/2022. Satellite remote sensing indices were used to map wetlands and characterize the vegetation condition in the landscape surrounding them. Landscape metrics were used to describe the habitat configuration around the wetlands.ResultsOur results show that landscape composition, configuration and function have significant effects on waterbirds (i.e., shorebirds, waterfowl, wading birds, and open-water birds). We found that wetland surface area and distance to the coast were important factors influencing the richness and abundance of waterbirds. Our results also indicate that landscape diversity is an important predictor of waterbird richness and abundance, and that there is a significant interaction between wetland surface area and distance to the nearest wetland in explaining the richness and abundance of waterbirds.ConclusionsThis study provides evidence that the richness and abundance of waterbirds are robustly dependent on the interaction between wetland surface area and distance to the nearest wetland. Furthermore, local wetland characteristics (wetland surface area and distance to the nearest coastline), landscape composition (forest area and urban area), landscape configuration (spatial heterogeneity), and landscape function (maximum and minimum NDVI), significantly affect wintering waterbird communities. This study also highlights the importance of large and connected wetlands in conserving various bird communities in Tunisian IBAs and provides recommendations for their conservation and sustainable management.

Uncovering habitat associations and thresholds—insights for managing breeding waterfowl in Eastern Canada

ContextUnderstanding how habitat influences species abundance is crucial in developing ecologically sound wildlife conservation management plans. Exploring habitat associations and ecological thresholds in species’ responses allows for better conservation and management on a landscape-scale.ObjectivesThis work aimed to identify habitat drivers and response thresholds of waterfowl and waterbird species’ densities in eastern Canada to support key landscape-level decisions for habitat conservation and wetland management.MethodsWe developed predictive abundance models for 17 species across eastern Canada from 2001 to 2015 using data from four regional surveys and identified areas where prioritizing enhancement of wetlands would increase the breeding density of five priority waterfowl species.ResultsHabitat associations and spatial abundance patterns varied across species, but most species responded strongly to forest composition, agriculture, and wetland features. Threshold effects occurred and varied among species, yet generally once 14% of a plot was covered in wetlands, positive effects of increased wetland diminished for most species. Our results allow for the targeting of investments in increasing wetland area along portions of eastern Canada that provide the best opportunities to increase breeding densities for priority waterfowl species.ConclusionsUnderstanding species-habitat associations and response thresholds allows for landscape management and planning and prioritization of limited resources. We suggest that management and wetland enhancement efforts for waterfowl in eastern Canada should be guided by predictive models and response thresholds of key habitat attributes to best prioritize actions that will have the biggest positive impact on multiple species.

Distribution Status of Invasive Alien Species in the Estuarine Wetlands in East and South Coast, Korea

Based on the results of survey on estuarine ecosystem conducted from 2021 to 2023, this study analyzed the distribution pattern of invasive alien species. A total of six invasive alien species (<i>Micropterus salmoides</i> [<i>M. salmoides</i>], <i>Lepomis macrochirus</i> [<i>L. macrochirus</i>], <i>Lithobates catesbeianus</i> [<i>L. catesbeianus</i>], <i>Trachemys scripta</i> [<i>T. scripta</i>], <i>Pseudemys concinna</i> [<i>P. concinna</i>], and <i>Pseudemys nelsoni</i> [<i>P. nelsoni</i>]) were identified across 118 estuarine wetlands. The survey revealed 960 individuals of <i>M. salmoides</i>, 2,596 individuals of <i>L. macrochirus</i>, 1,088 individuals of <i>L. catesbeianus</i>, and 44 individuals of <i>T. scripta</i>, while 1 individual of <i>P. concinna</i> and <i>P. nelsoni</i> were found. These invasive species were found to be densely distributed in estuarine wetlands in the Haenam and Goheung regions of the southern coast. Furthermore, the distribution density varied depending on the characteristics and locations of the estuarine wetlands. It was observed that the distribution density was higher in closed type than in open type, in riverine than in lacustrine, and in the south coast than in the east coast. Once the basic survey of estuarine wetlands located on the west coast is completed, a clearer understanding of the nationwide distribution characteristics of invasive alien species in estuarine wetlands can be achieved. This information will be crucial for formulating appropriate management strategies tailored to the characteristics of wetlands or coastal areas in the future.

Geospatial Assessment of Wetland Changes in the Fringe Area of Dhaka City: Past, Present and Future Scenarios

This study examines the changes in wetlands in the fringe area of Dhaka city using geospatial assessment techniques. The wetland in the area is crucial as they serve as a buffer zone for the Dhaka Metropolitan Area (DMA) and play a significant role in maintaining the region's ecological balance. Thirty-meter NASA Landsat 4-5TM and Landsat 8 OLI satellite imagery were used to extract wetland features in the fringe area of Dhaka city. The Modified Normalized Difference Water Index (MNDWI) was applied to delineate wetland features. Finally, ArcGIS geometric computing was used to detect yearly changes, and a Cellular Automaton (CA) Markov Model was applied to predict future transitions. The research findings reveal that wetlands in the Dhaka Metropolitan Area are declining at a rate of 1.1% between 1991 and 2016, indicating the urgency of addressing this issue to ensure the sustainability of the region's natural resources. The percentage of wetlands in the fringe area has been decreasing significantly over the years, with wetlands making up only 12.98% of the fringe area in 2022, down from 28.22% in 1989. This trend is predicted to continue, with wetlands accounting for only 8.02% of the total area by 2034. The strong negative correlation coefficient between the year and wetland area suggests that the trend of decreasing wetland is likely to continue unless significant measures are taken to protect wetlands. The study highlights the importance of conserving and restoring wetlands in Dhaka's fringe areas to maintain the ecological balance of the region and support the well-being of both humans and wildlife. The Dhaka University Journal of Earth and Environmental Sciences, Vol. 12(2), 2023, P 97-117

Low rate of population establishment of a freshwater invertebrate (Gammarus lacustris) in experimental conservation translocations

Conservation translocations may be a useful tool for the restoration of declining freshwater invertebrates, but they are poorly represented in the literature. We conducted a before‐after/control‐impact (BACI) experiment to test the efficacy of conservation translocation for re‐establishing abundant populations of the amphipod Gammarus lacustris, a declining species and wildlife food resource in depressional wetlands in the upper Midwest of the United States of America. Each study site (n = 19) contained at least one treatment wetland receiving translocated G. lacustris from a local donor and one control wetland. We selected study wetlands based on a suite of wetland characteristics and randomly assigned recipient versus control treatment. Gammarus lacustris was detected post‐translocation at only 2 of 22 recipient wetlands (1 of 19 sites). Overall, there was a statistical increase in G. lacustris density in recipient wetlands compared to controls; however, the results were of minimal biological significance due to being driven by a single site with low G. lacustris densities. Accordingly, our results suggest that future conservation translocations of amphipods might be successful if limited to recently restored wetlands or informed by a more complex habitat suitability model to differentiate dispersal limitations from habitat limitations. To develop such a model would involve identifying the fewest, most influential physical and biological factors (e.g. wetland size/structure, fish, aquatic vegetation, and water chemistry) from the numerous inter‐related factors that correlate with the abundance of naturally occurring G. lacustris; candidate wetlands to receive amphipods would be those for which the model predicts abundant G. lacustris but in which they do not presently occur.

Global annual wetland dataset at 30 m with a fine classification system from 2000 to 2022

Wetlands play a key role in maintaining ecological balance and climate regulation. However, due to the complex and variable spectral characteristics of wetlands, there are no publicly available global 30-meter time-series wetland dynamic datasets at present. In this study, we present novel global 30 m annual wetland maps (GWL_FCS30D) using time-series Landsat imagery on the Google Earth Engine platform, covering the period of 2000–2022 and containing eight wetland subcategories. Specifically, we make full use of our prior globally distributed wetland training sample pool, and adopt the local adaptive classification and spatiotemporal consistency checking algorithm to generate annual wetland maps. The GWL_FCS30D maps were found to achieve an overall accuracy and Kappa coefficient of 86.95 ± 0.44% and 0.822, respectively, in 2020, and show great temporal variability in the United States and the European Union. We expect the dataset would provide vital support for wetland ecosystems protection and sustainable development.

Climate change will reduce North American inland wetland areas and disrupt their seasonal regimes

Climate change can alter wetland extent and function, but such impacts are perplexing. Here, changes in wetland characteristics over North America from 25° to 53° North are projected under two climate scenarios using a state-of-the-science Earth system model. At the continental scale, annual wetland area decreases by ~10% (6%-14%) under the high emission scenario, but spatiotemporal changes vary, reaching up to ±50%. As the dominant driver of these changes shifts from precipitation to temperature in the higher emission scenario, wetlands undergo substantial drying during summer season when biotic processes peak. The projected disruptions to wetland seasonality cycles imply further impacts on biodiversity in major wetland habitats of upper Mississippi, Southeast Canada, and the Everglades. Furthermore, wetlands are projected to significantly shrink in cold regions due to the increased infiltration as warmer temperature reduces soil ice. The large dependence of the projections on climate change scenarios underscores the importance of emission mitigation to sustaining wetland ecosystems in the future.

Litter decomposition and nutrient dynamics of four macrophytes in intact, restored, and constructed freshwater marshes of Canada

The restoration and construction of wetlands offer opportunities to rewet soils, inhibit decomposition, and enhance nutrient retention in decomposing litters. Here, we report the decomposition rates and nutrient dynamics of macrophyte litters in intact, restored, and constructed wetlands. A 2.1‐year litterbag experiment of four common freshwater macrophytes (Phalaris arundinacea, Phragmites australis, Scirpus cyperinus, and Typha latifolia) was conducted in eight freshwater marshes (three intact, four restored, and one constructed) within three sites in Manitoba and Ontario, Canada, which varied in restoration age, inundation periods, and surrounding land uses. Litter mass loss and N and P dynamics were measured. Litter decomposition rates (k) followed the order of P. arundinacea (0.42 ± 0.03 year−1) > T. latifolia (0.31 ± 0.03 year−1) > P. australis (0.19 ± 0.01 year−1) > S. cyperinus (0.13 ± 0.01 year−1) in most wetlands and were positively correlated to the initial litter N concentration. Litters decomposed fastest under seasonally inundated conditions rather than permanent inundation. N and P retention in litters were significantly affected by both initial litter N and P concentration and wetland surrounding land uses. After 2.1 years of decomposition, the N:P ratio of all litters converged to 20 to 28:1, regardless of the initial litter N:P ratio or N or P concentrations. The effectiveness of wetland restoration in slowing decomposition and enhancing nutrient accumulation depends on the quality of the input litters and wetland characteristics, including inundated periods and surrounding anthropogenic disturbances.

Informing the Conservation of Ephemerally Flooded Wetlands Using Hydrologic Regime and LiDAR-Based Habitat Assessments

Integrated assessments of wetland hydrologic regimes and other environmental factors are key to understanding the ecology of species breeding in ephemerally flooded wetlands, and reproductive success is often directly linked to suitable flooding regimes, both temporally and spatially. We used high-resolution Light Detection and Ranging (LiDAR) data to develop bathymetric stage–flooded area relationships, predict spatial extent of flooding, and assess vegetation structure in 30 pine flatwoods wetlands. For a subset of wetlands with monitoring wells, we then integrated bathymetric and water level data to create multi-year time series of daily flooded areas. We then related the observed flooded areas to topographic and landscape metrics to develop models predicting flooded extents in wetlands without monitoring wells. We found that stage–area curves varied depending on wetland size and bathymetry, such that a one-cm increase in water depth could generate flooded area increases ranging from hundreds to thousands of square meters. Flooded areas frequently fragmented into discrete flooded patches as wetlands dried, and there was a weak positive correlation between hydroperiod and mean flooded area across multiple years (r = 0.32). To evaluate the utility of using LiDAR-derived data to support the conservation of wetland-breeding species, we combined metrics of flooding and vegetation to map potentially suitable habitat for the imperiled reticulated flatwoods salamander (Ambystoma bishopi). Overall, projects focusing on the ecology of wetland-breeding species could gain a broader understanding of habitat effects from coupled assessments of bathymetry, water level dynamics, and other wetland characteristics.

Zoning, Land Use Management and Nature-Based Solutions in Urban Planning, Where Sri Lanka is Standing

Urbanization rapidly changes the land use pattern in Sri Lanka. Cities are important economic centers and provide opportunities for quality of life. Zoning creates prospering urban planning environments, improves construction permit efficiency, enables agency coordination, and provides widespread participation in urban planning. A comprehensive zoning plan with environmentally conscious zoning contributes to the conservation of natural resources, enhances the ability of climate change adaptation and mitigation, fosters a greener urban environment, and ensures urban sustainability. Nature-based Solutions (NbS) are incorporated by nature; use, or mimic, natural processes to contribute to improvement in given landscapes, small or large scale. Attention to NBS has significantly increased in the recent past and is trying to mainstream NbS into a wide range of policies, and urban planning. This study aimed to explore how zoning and NbS can be incorporated in an urban setting to increase urban resilience in water-born cities. The administrative capital of Sri Lanka, Sri Jayawardhanapura-Kotte was selected due to unique inland urban wetland characteristics and vulnerability to wetland ecosystem due to rapid development in the area. Sri Jayawardhanapura-Kotte is rich with its unique landscape and is a part of Ramsar-Colombo wetlands. The Sri Jayawardhanapura-Kotte Capital City Development Plan (the Plan) 2020 and other relevant national policies were assessed in terms of zooning and application of NbS as a strategy of a sustainable and resilient city. Environmental changes and disaster risk areas were assessed (spatial and temporal changes) utilizing earth observation and GIS techniques, and secondary data were obtained from official records and reports. Sri Jayawardhanapura-Kotte covers 78% of the Greater Colombo flood retention area, and 55% of the area is suitable for flood retention. However, 40% of Colombo wetlands have been lost during the last 30 years due to urbanization. Data shows that most of the wetlands are being filled for infrastructure development, including housing, and it is critically important to conserve remaining wetlands in the area with strict regulations including zoning. The Plan has no signs of incorporating or recognizing NbS in the objectives, strategies, and actions for restoration wetlands, proper zoning system for flood mitigation. Analysed policies lack recognition or incorporation of zoning for environmental conservation and disaster risk reduction. The importance of urban areas for future cannot be underestimate and proper urban planning is a necessity in Sri Lanka for mitigate precent anthropogenic climate change impacts ranging but not limited to urban flooding to public health.
 
 Keywords: Urban planning, Zoning, Nature-based Solutions, Resilience, water-born cities

Brine formation in cold desert, shallow groundwater systems: Antarctic Ca-Cl brine chemistry controlled by cation exchange, microclimate, and organic matter

Groundwater in the McMurdo Dry Valleys of Antarctica is commonly enriched in calcium and chloride, in contrast to surface and groundwater in temperate regions, where calcium chemistry is largely controlled by the dissolution of carbonates and sulfates. These Antarctic Ca-Cl brines have extremely low freezing points, which leads to moist soil conditions that persist unfrozen and resist evaporation, even in cold, arid conditions. Several hypotheses exist to explain these unusual excess-calcium solutions, including salt deliquescence and differential salt mobility and cation exchange. Although the cation exchange mechanism was shown to explain the chemistry of pore waters in permafrost cores from several meters depth, it has not been evaluated for near-surface groundwater and wetland features (water tracks) in which excess-calcium pore-water solutions are common. Here, we use soluble salt and exchangeable cation concentrations to determine whether excess calcium is present in water-track brines and if cation exchange could be responsible for calcium enrichment in these cold desert groundwaters. We show that calcium enrichment by cation exchange is not occurring universally across the McMurdo Dry Valleys. Instead, evidence of the present-day formation of Ca-Cl−rich brines by cation exchange is focused in a geographically specific location in Taylor Valley, with hydrological position, microclimate, soil depth, and organic matter influencing the spatial extent of cation exchange reactions. Up-valley sites may be too cold and dry for widespread exchange, and warm and wet coastal sites are interpreted to host sediments whose exchange reactions have already gone to completion. We argue that exchangeable cation ratios can be used as a signature of past freeze-concentration of brines and exchange reactions, and thus could be considered a geochemical proxy for past groundwater presence in planetary permafrost settings. Correlations between water-track organic matter, fine sediment concentration, and cation exchange capacity suggest that water tracks may be sites of enhanced biogeochemical cycling in cold desert soils and serve as a model for predicting how active layers in the Antarctic will participate in biogeochemical cycling during periods of future thaw.

Influence of Wetland and Landscape Characteristics on Freshwater Turtle Relative Abundance and Movement Patterns in West Virginia, USA

Wetland management practices often alter habitat characteristics to improve the function of the wetland (e.g., removing emergent vegetation for aesthetics or dredging for fish stocking), potentially at the cost of reducing habitat quality for wetland-dependent species such as freshwater turtles. We identified wetland and surrounding landscape characteristics related to painted turtle (Chrysemys picta) and snapping turtle (Chelydra serpentina) relative abundance and snapping turtle movement among wetlands. We surveyed turtles at 29 wetland sites (0.04–1.71 ha) in a mixed-use watershed in north-central West Virginia, USA, where hardwood forests and wetlands have been heavily fragmented by agriculture and roads. We also applied radio transmitters to 33 adult snapping turtles (17 females and 16 males) across 17 wetlands. Snapping turtle relative abundance was best estimated with mean substrate depth, mean wetland depth, and minimum distance from roads. Painted turtle relative abundance was best estimated with the null model. We documented movement among wetlands for 22 snapping turtles (67%), including 10 females and 12 males. The probability of inter-wetland movement decreased with increased minimum distance from wetlands. Our results suggest that the focal turtle species readily used shallow, mucky wetlands with deep substrate and that increasing the density of wetlands could increase snapping turtle population connectivity. Managers could consider restoring a diversity of wetland types that result in reduced travel distance between wetlands and that collectively have characteristics conducive to multiple species.

Vegetation and inundation characteristics of waterbird breeding sites in the Murray–Darling Basin, Australia

Context The Murray–Darling Basin serves as a crucial habitat for aggregating waterbirds; however, decades of large-scale regulation of rivers and water resources have adversely affected waterbird breeding in the Basin. Aims To understand the characteristics of wetlands that attract and support aggregating waterbirds, focusing on identifying environmental conditions conducive to waterbird breeding. Methods In total, 52 wetland sites across the Murray–Darling Basin, with high waterbird abundances, were identified, of which 26 supported waterbird breeding. Classification models were developed using temporally static and dynamic environmental datasets to discern wetland characteristics associated with waterbird breeding. Key results Analyses showed that wetlands supporting waterbird breeding contained a maximum inundated area of ‘other shrublands’ exceeding 3.635 km2 and variation in normalised difference vegetation index, possibly reflective of a ‘boom and bust’ ecological response. Conclusions Understanding the habitat requirements of wetlands to prompt waterbird breeding is critical for effective environmental water management and conservation strategies. Implications Targeted wetland management and environmental water allocation to support waterbird breeding populations in the Murray–Darling Basin is essential for continued waterbird breeding. There is a need for continued research to refine management strategies and ensure the long-term sustainability of waterbird populations in the face of ongoing environmental challenges.