High Water Levels Research Articles

Single-grain luminescence dating of Manas Lake paleoshorelines reveals late quaternary glacial meltwater forced lake level highstand in arid Central Asia

The spatiotemporal patterns of late Quaternary lake evolution, along with their responses to climatic changes and glacial meltwater in the westerlies-dominated Central Asia, remain unclear primarily due to the lack of well-dated records spanning across glacial and interglacial cycles. In this study, we investigated five well-preserved paleolake shoreline sequences, 15–27 m above the modern lake basin of the now-dry Manas Lake, a representative terminal lake in the Junggar Basin of arid Central Asia. Both single aliquot and single-grain K-feldspar post-infrared infrared stimulated luminescence (pIRIR) dating protocols were applied to 26 shoreline samples to reconstruct a lake level variation for Manas Lake over the past 90 kyr. The reliability of the K-feldspar pIRIR dating was tested through assessment of luminescence characteristics and comparison of single-grain and single-aliquot K-feldspar pIRIR Des. The results indicate that the highest water levels (∼25 m deep) occurred during late Marine Isotope Stage (MIS) 5 (∼80 ka) and MIS 3 (31–27 ka). A lake level 20 m above modern lake basin (a.m.l.b.) occurred from the last deglaciation to the early Holocene (14–10 ka) and again in the late Holocene (3.4–0.3 ka). The lake level changes of Manas Lake are decoupled from observed Westerlies precipitation changes over the past 90 kyr. This decoupling suggests enhanced glacial meltwater sourced from the high Tianshan Mountains, triggered by higher mean summer temperatures, worked together with Westerlies precipitation drove periods of lake level highstand in Manas Lake during late MIS 5, late MIS 3, and early Holocene periods.

Inter-annual changes in zooplankton in the Volga delta kultuk zone in summer (low-water period)

The paper presents the results of our studies of inter-annual changes in the structure of summer zooplankton in the kultuk zone of the Volga delta depending on hydrological and meteorological conditions. The study shows the main trends in zooplankton differences in a series of low-water years. It was found that in low-water years in the kultuk zone with low runoff, short floods and weak watering of floodplain territories, zooplankton was characterized by low species richness, reduced average individual mass of crustaceans and the number of Rotifera, but a high proportion of the number of juvenile Copepoda. In the year when the water level decreased before the flood during the period of temperature increase, and then a rapid rise with the inflow of cold waters and the removal of fish larvae, zooplankton was characterized by a minimum species richness and quantitative values of Rotifera, but increased biomass of Cladocera and the Shannon index. In every low-water year, with a stable and relatively high water level before the flood, fish spawning in the kultuk zone, biomass of zooplankton reduced due to Cladocera, and the number of species in the sample. In every mid-water year, the flood had the largest runoff and prolonged, increased flooding of the floodplain, zooplankton was characterized by the maximum total and specific species richness, abundance of Rotifera, total biomass on account of Cladocera, and the individual mass of crustaceans, the Shannon index, but the minimum proportion of juvenile Copepoda.

Different effects of seasonal impoundment and land use change on microbiome in a tributary sediment of the three gorgers reservoir

Anthropogenic activities significantly impact river ecosystem nutrient fluxes and microbial metabolism. Here, we examined the seasonal and spatial variation of sediments physicochemical parameters and the associated microbiome in the Pengxi river, a representative tributary of Three Gorges Reservoir, in response to seasonal impoundment and land use change by human activities. Results revealed that seasonal impoundment and land use change enhanced total organic carbon (TOC), total nitrogen (TN) and ammonium nitrogen (NH4+-N) concentration in the sediment, but have different effects on sediment microbiome. Sediment microbiota showed higher similarity during the seasonal high-water level (HWL) in consecutive two years. The abundant phyla Acidobacteria, Gemmatimonadetes, Cyanobacteria, Actinobacteria and Planctomycetes significantly increased as water level increased. Along the changes in bacterial taxa, we also observed changes in predicted carbon fixation functions and nitrogen-related functions, including the significantly higher levels of Calvin cycle, 4HB/3HP cycle, 3HP cycle and assimilatory nitrate reduction, while significantly lower level of denitrification. Though land use change significantly increased TOC, TN and NH4+-N concentration, its effects on spatial variation of bacterial community composition and predicted functions was not significant. The finding indicates that TGR hydrologic changes and land use change have different influences on the carbon and nitrogen fluxes and their associated microbiome in TGR sediments. A focus of future research will be on assessing on carbon and nitrogen flux balance and the associated carbon and nitrogen microbial cycling in TGR sediment.

The Role of Advection in Storm Surge for Hurricane Michael (2018)

AbstractHurricane Michael (2018) made landfall near Mexico Beach, FL, as a Category 5 hurricane, with gauge‐measured water levels over 4 m. Wind and pressure fields were created by blending a parametric near‐field model with a gridded far‐field model. Winds and modeled water levels were well validated across Michael's large impact a‐ea. A detailed analysis of the coastal surge caused by Michael demonstrates that advection contributed significantly to Michael's highest water levels and the timing of the water level across a large portion of the Michael impact area. A momentum balance in a streamwise‐normal coordinate system demonstrates that the advection contributions due to spatial gradients in the flow are identified with streamwise convergence/expansion of the flow field (Bernoulli acceleration) and curvature in the flow field (centrifugal acceleration). These effects are created by the regional geometry and the storm's wind field and are most likely to affect back barrier water levels and along curved coastlines. These findings provide an improved understanding of the role of advection in determining storm surge and, thus, the importance of including it in storm surge models.

STUDY RE-ANALYSIS OF HIGH WAVE DEFORMATION IN RE-DESIGN COASTAL REVETMENT PROTECTION OF RAJABASA BEACH KALIANDA

The eruption of Mount Krakatau in 2018, along with high waves, has impacted the coastal conditions of Kalianda Beach. The parameters for planning the revetment include significant wave height, highest high water level (HHWL), refraction and shoaling coefficients, wave set-up, and SLR. Wave data processing was conducted using the FT Type I. The extreme wave 50-year period has a height (Hr) of 2.22 m and a period (Tr) of 14.67 s. The wave transformation coefficients for refraction and shoaling, which are 0.74 and 1.44 respectively, lead to a deformation wave height of 2.19 m at a depth of 5 m. Admiralty tide analysis yielded a tidal range element at MSL of 0.94 m, which serves as the datum for elevation point 0. The HHWL from MSL is 0.73 m, wave set-up is 0.58 m due to breaking waves at 3.43 m, and SLR is 0.16 m, leading to a DWL of 1.46 m. The wave run-up varies according to the type of revetment, boulder type elevations id 4.60 m, tetrapod type is 3.80 m, and dolos type is 4.40 m. Differences elevation are attributed to different wave run-up every type of revetment material, run-up of the type material boulder is 2.83 m, run-up of tetrapod is 2.08 m, and dolos is 2.67 m.

Large shallow lake response to anthropogenic stressors and climate change: Missing macroinvertebrate recovery after oligotrophication (Lake Balaton, East-Central Europe)

East-Central Europe's largest shallow lake, Balaton, experienced strong eutrophication in the 1970–80s, followed by water quality improvement and oligotrophication by 2010 CE. Recently however, repeated cyanobacterial blooms occurred and warned that internal P-recycling can act similarly to external P load, therefore we need a better understanding of past water level (WL) and trophic changes in the lake. In this study we discuss the last 500-yr trophic, WL and habitat changes of the lake using paleoecological (chironomids, pollen) and geochemical (sediment chlorophyll, TOC, TS, TN, C/H ratio, major and trace element) methods. We demonstrate that the most intensive and irreversible change in the macroinvertebrate fauna occurred during the period of economic boom between the First and Second World War (∼1925–1940 CE), when large-scale built-in and leisure use of the lake has intensified. At that time, the Procladius-Microchironomus-Stempellina dominated community transformed to Procladius-Chironomus plumosus-type-Microchironomus community that coincided with land use changes, intensified erosion and water-level regulation in the lake with the maintenance of year-round high WL. This was followed by the impoverishment and population size decrease of the chironomid fauna and Procladius dominance since 1940 CE, without any recovery after 1994 CE despite the ongoing oligotrophication. Accelerated rate of change and turnover of the fauna was connected to an increase in the benthivorous fish biomass and eutrophication. The basin lost almost completely its once characteristic Stempellina species between 1927 and 1940 CE due to trophic level increase and seasonal anoxia in the Szemes Basin. Reference conditions for ecosystem improvement were assigned to 1740–1900 CE. We conclude that in spite of the ongoing oligotrophication, the re-establishment of the Procladius-Microchironomus-Stempellina assemblage is hampered, and requires fish population regulation.

Increasing The Bearing Capacity of Foundations on Sandy Soil with High Water Levels Using Mini-pile

In the Kediri Regency area, it is planned to build a 3-story shophouse as one of the supporting facilities and the community’s economic needs. This area has sandy soil conditions and a high-water table. The purpose of this study was to calculate the carrying capacity of the soil in constructing a 3-story shophouse using the Terzaghi, Mayerhof, and Hansen methods. The condition of the soil with a relatively high groundwater table made the implementation of the footplate foundation less effective, so a modification of the foundation was made, which added three mini-piles measuring 0.4x0.4x1.5m, with a design load supported by the foundation of 100 t/m². Calculations with the Mayerhof and Hansen methods have nearly identical results but have not fulfilled the planned load. At a foundation depth of up to 3 m with an SF value of 3, for the Terzaghi method: 107.75 t/m2, the Mayerhof method: 92.51 t/m2, and the Hansen method: 94.68 t/m2. The results can be used as an alternative in constructing a 3-story shophouse with sandy soil conditions and high groundwater levels. This research can also be a reference for other regions facing similar problems.

SedaDNA reveals mid-to late Holocene aquatic plant and algae changes in Luanhaizi Lake on the Tibetan Plateau

Aquatic plants and algae are the primary producers in lake ecosystems, providing the organic matter and oxygen necessary for the nutrients and energy of most organisms. Climatic and environmental changes may have irreversible impacts on aquatic plants and algae communities, while direct observation and experiments can only provide a short-term perspective. As a record of the long-term variation of the ecosystem, sedimentary ancient DNA (sedaDNA) could offer evidence about aquatic plants and algae change over extended time scales and improve the taxonomic resolution than the traditional morphology methods such as pollen and macrofossil. In this study, we employed metagenomics in sedaDNA from Luanhaizi Lake (northeastern Tibetan Plateau) since 8.2 cal kyr BP, to characterize the aquatic plant and algae communities' response to the climatic and environmental change over an extended historical timeline. The results demonstrate that during 8130–4620 cal yr BP, pondweed (Stuckenia) was the dominating aquatic plant in Luanhaizi Lake, with a generally low diversity of aquatic plants and algae. During 3670–2290 cal yr BP, Luanhaizi Lake had an increased diversity and triggered a shift from Stuckenia to Eurasian watermilfoil (Myriophyllum). During 1810–50 cal yr BP, with the warming process, cyanobacteria appeared and diversity peaked. Correlation and redundancy analyses show that this process might be related to climatic and environmental changes, such as decreased salinity, increased temperature, and higher water levels. Our results signify that aquatic plants and algae communities are sensitive to paleoclimatic and environmental change, in the context of global warming, the studies on the past dynamics of aquatic plants and algae will help predict the potential changes of the lake ecosystem on the northeastern Tibetan Plateau in the future.

Modeling water hyacinth (Eichhornia crassipes) distribution in Lake Tana, Ethiopia, using machine learning

Aquatic invasive plant, water hyacinth poses serious environmental and socioeconomic challenges. Understanding and predicting the spatiotemporal distribution of this species is important for reducing its environmental impact. Therefore, the present study aimed to model the distribution of water hyacinths in an important ecological region (Lake Tana) of Ethiopia using four machine learning models. We used 11 variables obtained from Sentinel-1 SAR bands, Sentinel-2A bands and indices, and bioclimate data sources. The models use 458 presence and 458 randomly generated pseudoabsence data as response variables and employ a tenfold bootstrap sampling method. The area under the curve (AUC), receiver operator curve (ROC), true skill statistics (TSS), coefficient of rank correlation (COR), sensitivity, specificity, and kappa coefficient were used to evaluate the models. The findings demonstrate that the random forest model outperforms the other models, with AUC values of 0.93 and 0.95, TSS values of 0.77 and 0.82, and kappa values of 0.76 and 0.82 in the wet and dry seasons, respectively. B12 (16% and 20%), NDWI (15% and 12%), mean annual temperature (13% and 14%), and B5 (11% and 12%) were found to be the most relevant variables during the wet and dry seasons, respectively. Water hyacinths have greater spatial coverage during the wet season than during the dry season because of high rainfall, high water levels and nutrient runoff. We can conclude that to detect and predict the spatiotemporal conditions of water hyacinth accurately, integrating Sentinel image indices and bands with bioclimatic variables and using machine learning models are crucial.

Is larger always lekker? A comparative analysis of South Africa's water user associations (WUAs) and catchment partnerships (CPs) and their impact on water, energy, and food (WEF) security

Complexities in water, energy, and food (WEF) governance provide varied systems and pathways that shape welfare outcomes. The biggest question relates to the scale and complexities in resource management and governance, which reaches a certain equilibrium to achieve maximum welfare benefits. This is a proposition that is assessed in this study which sought to compare the WEF welfare outcomes of jurisdictions under Water User Associations (WUAs) and Catchment Partnerships (CPs). The study used a multi-stage purposively sampled cross-sectional survey of 1184 households from Greater Taung and Magareng Local Municipalities (Vaalharts Water User Association) and Matatiele Local Municipality (uMzvimvubu Catchment Partnership) in South Africa. The Household Water Insecurity Experiences, Household Multi-Dimensional Energy Poverty Index and Household Food In-Access Scale, Min-Max normalization and Propensity Score Matching were used to analyze the data. There was association between jurisdiction and the level of WEF security. Households under the jurisdiction of a WUA experienced 13.8%, 6.8% and 9.3% higher levels of water, energy, and food insecurity, respectively. The study concludes that households under the jurisdiction of a CP had higher levels of WEF security, with complexities or lack thereof resulting in higher welfare outcomes. Therefore, larger is not always lekker. The study recommends either (i) scaling down of WUA to CP and/or (ii) diversifying by increasing the breadth and scope of stakeholders within WUA. The governance systems should be integrated in an evaluation to ascertain any impact on the welfare outcomes.

A New Numerical Method to Evaluate the Stability of Dike Slope Considering the Influence of Backward Erosion Piping

Backward erosion piping, a soil erosion phenomenon induced by seepage, compromises the stability of water-retaining structures such as dikes. During floods, the seepage in the dike body increases due to high water levels, which directly affects the progression of the piping channel. The formation of the piping channel then impacts the stability of the dike. In this paper, an improved piping model that considers the impact of seepage in the dike body is proposed based on Wewer’s model. Specifically, we added a seepage field of the dike body to the original model to account for the impact of dike-body seepage on the evolution of piping. The seepage field of the dike body is solved using Darcy’s law and the continuity equation for unsaturated porous media. In addition, this approach also incorporates the coupling effect of seepage stress. The accuracy of the model was verified through comparing the calculated results with the IJkdijk experiment and Wewer’s results. The effects of BEP on dike stability were investigated using the proposed improved piping model. The two major conclusions of the study are that (1) the incorporation of unsaturated seepage enhanced the performance of the piping model, allowing it to more accurately simulate the development of pipe length and the changing of pore pressure; and (2) the formation of the pipe impacted dike stability, leading to a substantial reduction in the safety factor of the dike slope.

Effect of Coal Mining Subsidence on Soil Enzyme Activity in Mining Areas with High Underground Water Levels

In order to investigate the changes in soil enzyme activity and their influencing factors in coal mining subsidence areas with high underground water levels, in this study, we collected soil samples at different depths (SL: 0–20 cm; ML: 20–40 cm; DL: 40–60 cm) in a deep coal seam subsidence area (T1), a shallow coal seam subsidence area (T2), and control non-subsidence areas (W1 and W2) in eastern China. Soil physicochemical properties and enzyme activities were determined, and the mechanism of the latter’s response to coal mining subsidence was investigated based on correlation analysis, redundancy analysis, and structural equation modeling. The results show the following: (1) In the coal mining subsidence areas, the soil pH value (pH), soil available nitrogen (AN), available phosphorus (AP), available potassium (AK), and soil organic matter (SOM) contents were lower than those in the non-subsidence areas, while the soil water content (SWC) and bulk density (BD) were higher than those in the non-subsidence areas and increased with depth. (2) The activities of soil urease (URE), sucrase (SUC), alkaline phosphatase (ALP), and catalase (CAT) gradually decreased with depth and were all lower than those in the non-subsidence areas; the largest decreases with respect to the latter were 24.33%, 18.73%, 38.89%, and 5.88%, respectively. (3) The soil nutrient environment had a highly significant and direct positive effect on enzyme activity, with AN, AP, and SOM contents having the greatest impact. (4) Soil BD had a highly significant and direct negative effect and an indirect negative effect (by affecting nutrients) on enzyme activity. The results of this study on the effects of soil physicochemical properties on enzyme activity provide a basis for the ecological restoration of mines.

Breaching of the Sillon de Talbert gravel spit (North Brittany, France) and coastal flooding risk assessment

Coastal barriers are a natural defence against the marine submersion of low-lying back-barrier areas. In March 2018, a breach opened up in the proximal section of the Sillon de Talbert spit barrier (North Brittany, France), causing great concern among local residents and elected representatives. A study to assess the risk of submersion of the low-lying areas of the Laneros Peninsula, located behind the barrier, was carried out in 2020. Hydrodynamic conditions (waves, currents, and water levels) were modeled using Telemac-2D coupled with the phase-averaged wave model TOMAWAC. Simulations were compiled for the storm of February 1, 2014, corresponding to the most morphogenic event to occur in the last two decades. Five topomorphological configurations were considered for the numerical simulations: configurations #1 and #2 correspond to the ante-breach and post-breach morphological settings, while configurations #3, #4, and #5 correspond to hypothetical scenarios, from the enlargement of the breach (from 300 to 500 m width), to complete crest lowering of the barrier after a complete removing of the crest due to catastrophic overwash events. The results show that the breach accelerates the draining of the back-barrier sandflat, thereby reducing the height of extreme water levels at the coastline. This is mainly due to different tidal impacts on either side of the barrier, with a higher water level and the tidal peak occurring 15 min later and the on the back-barrier than on the ocean-side zone. As a result, ebb currents begin to flow before the high tide level is reached, inducing a significant draining with a lowering of the extreme water level at the back-barrier zone. However, these simulations do not take into account the effects of climate change over the coming years, in particular the future rise in sea level and/or the acceleration of erosion processes already underway.

Assessing alternative lake management actions for climate change adaptation.

Lake management actions are required to protect lake ecosystems that are being threatened by climate change. Freshwater lakes in semiarid regions are of upmost importance to their region. Simulations of the subtropical Lake Kinneret project that rising temperatures will cause change to phytoplankton species composition, including increased cyanobacteria blooms, endangering lake ecosystem services. Using lake ecosystem models, we examined several management actions under climate change, including two alternatives of desalinated water introduction into the lake, hypolimnetic water withdrawal, watershed management changes and low versus high lake water level. To account for prediction uncertainty, we utilized an ensemble of two 1D hydrodynamic-biogeochemical lake models along with 500 realizations of meteorological conditions. Results suggest that supplying desalinated water for local use, thus releasing more natural waters through the Jordan River, increasing nutrient flow, may reduce cyanobacteria blooms, mitigating climate change effects. However, these results are accompanied by considerable uncertainty.

Evaluation of Active and Passive UAV-Based Surveying Systems for Eulittoral Zone Mapping

Abstract. The eulittoral zone, which alternates between being exposed and submerged, presents a challenge for high-resolution characterization. Normally, its mapping is divided between low and high water levels, where each calls for a different type of surveying instrument. This leads to inconsistent mapping products, both in accuracy and resolution. Recently, uncrewed airborne vehicle (UAV) based photogrammetry was suggested as an available and low-cost solution. However, relying on a passive sensor, this approach requires adequate environmental conditions, while its ability to map inundated regions is limited. Alternatively, UAV-based topo-bathymetric laser scanners enable the acquisition of both submerged and exposed regions independent of lighting conditions while maintaining the acquisition flexibility. In this paper, we evaluate the applicability of such systems in the eulittoral zone. To do so, both topographic and topo-bathymetric LiDAR sensors were loaded on UAVs to map a coastal region along the river Rhein. The resulting point clouds were compared to UAV-based photogrammetric ones. Aspects such as point spacing, absolute accuracy, and vertical offsets were analysed. To provide operative recommendations, each LiDAR scan was acquired at different flying altitudes, while the photogrammetric point clouds were georeferenced based on different exterior information configurations. To assess the riverbed modelling, we compared the surface model acquired by the topo-bathymetric LiDAR sensor to multibeam echosounder measurements. Our analysis shows that the accuracies of the LiDAR point clouds are hardly affected by flying altitude. The derived riverbed elevation, on the other hand, shows a bias which is linearly related to water depth.

Temporal and spatial variation in water quality in the Son La hydropower Reservoir, Northwestern Vietnam

The Son La hydropower reservoir (S.L.R.) is the largest water reservoir in Vietnam. Da River water has been treated for drinking and domestic purposes; water quality management is essential for the safety of ecosystems and human health. This study was conducted to determine changes in water quality indicators [pH, dissolved Oxygen (D.O.), total suspended solids (T.S.S.), chemical oxygen demand (C.O.D.), ammonium (NH4+), nitrite (NO2-), and coliform] in the Da River in 2010 and the Son La hydropower reservoir during 2014-2023. The results of mean annual values of Da river water quality and Son La hydropower reservoir were, specifically: pH (7.8; 7.4), D.O. (4.3; 6.2), T.S.S. (112; 5), C.O.D. (15; 8.7), NH4+ (0.17; 0.3), NO2- (0.009; 0.04), and coliform (1,723; 747). Water quality parameters significantly varied between rive and reservoir water: D.O., T.S.S., C.O.D., and Coliform. pH, T.S.S., and C.O.D. slightly decreased; however, Dissolved oxygen (D.O.), NH4+, NO2-, and coliform demonstrated an increasing trend during 2014-2023. The impact of the Son La Dam (S.L.D.) on water quality was relatively straightforward: increasing the concentration of dissolved oxygen and the self-cleaning ability of pollutants. Periodic water impoundment was divided (April to August) into a low water level of 175 m, impoundment (January to March), a median water level of 190m, and a high water level of 215 m (September to December) to period. However, the impact of the staged impoundment on water quality, especially in 2014-2023, remains unclear, except D.O., T.S.S., NH4+, NO2- and Coliform exceeded limits or were lower is not significant for living water under the Vietnam regulation, specifically: D.O. (5.36, 5.52; ≥ 6), T.S.S. (25.13; ≤ 25), NH4+ (0.3331; 0.3), NO2- (0.0504; 0.05), coliform (1,018.5; ≤ 1,000). Results from the current study provide valuable information for reservoir and river water pollution source management and reduce potential risks to exposed ecosystems, livelihoods, and human health.

British surveillance of postwar Soviet radio jamming: US–UK intelligence relations and interference detection at BBC Tatsfield, 1948-1949

ABSTRACT Following World War II, the BBC, better known for radio programme broadcasts, continued its long-standing work of radio spectrum surveillance at the specialized receiving and measurement facility located at Tatsfield. Both before and after Soviet jamming of US and British Russian-language broadcasts escalated in April 1949, Tatsfield catalogued the technical characteristics of jamming signals. BBC engineers, experienced in interpreting types and sources of radio interference, issued fortnightly summaries with interpretations of these technical observations. US intelligence agencies knew of Tatsfield’s findings, but differing perspectives in Washington and London resulted in divergent responses to the technical intelligence data. With rising tensions in wider Anglo-American intelligence relations, fueled by the Soviet weapons program and security breaches, such differences presaged separate approaches to Soviet communications threats. US agencies received greatly increased funding, while the BBC’s budget struggles persisted. Even so, interference detection was a high-water mark in Britain’s early Cold War intelligence work.

Developmental plasticity to desiccation risk in tadpoles of a tropical inselberg specialist

Developmental plasticity evolves in heterogeneous environmental conditions as long as individuals can accurately perceive them. A paradigmatic example of developmental plasticity is the ability of amphibian larvae to alter growth and development in response to the risk of pond drying. Such responses are often found in amphibian species breeding in highly dynamic water bodies with high desiccation risk. The inselbergs of the Guianan Shield are rocky outcrops with extremely high and fluctuating temperatures and a marked seasonality in precipitation. During the rainy season, eroded depressions form precipitation-dependent pools with a high and variable risk of desiccation within the timeframe of a few days. The frog Leptodactylus lithonaetes specializes in breeding in this extreme environment, and its tadpoles are thus forced to cope with desiccation risk by adjusting their developmental trajectories and physiological performance. We experimentally assessed the effect of different levels of desiccation risk, under controlled temperature conditions, on developmental rate, growth, and temperature-dependent locomotor performance in tadpoles of Leptodactylus lithonaetes. We did not find an effect of desiccation risk on developmental rate, but under simulated drying conditions, tadpoles showed larger body size, greater body mass, and enhanced locomotor performance compared to constant (high or low) water levels. These results suggest that drying pools offer cues that trigger developmental and behavioral changes in these tadpoles, enabling them to enhance growth over a short time span without accelerating development. We discuss the potential compensatory mechanisms behind these responses and highlight the need for further investigations in species with semiterrestrial life histories in extreme environments.

Natural disturbance allows multiple anuran taxa to persist in a dynamic wetland complex

AbstractThe maintenance of biological diversity is frequently enhanced in a heterogenous landscape by some level of disturbance. Thus, when a landscape becomes stabilized and homogenized through the spread of an invasive plant species, there may be consequences for native biodiversity, particularly for those biotas that depend on the pre‐existing, natural disturbance regime of that landscape. At Long Point, Ontario, Canada, a sandspit in Lake Erie, the community of anuran amphibians experienced the co‐incidence of 2 major disturbance events, 1 anthropogenic and 1 natural: an intervention to remove the invasive form of the common reed (Phragmites australis australis) and a spate of extensive dune washouts caused by high water levels and storms. As a result of the unequal distribution of disturbance in the landscape, different areas were affected by only the dune washouts, only the common reed treatment, both disturbances, or neither disturbance. From May to August 2021, we explored how the disturbances affected the resident frog and toad species habitat associations in the 4 different disturbance conditions in the landscape. By means of minnow traps, acoustic surveys, and visual surveys, we determined that the dune washouts had a greater influence on resident anurans than the common reed treatment. Ranid frogs (Ranidae) tended to inhabit non‐washout sites, whereas Fowler's toads (Anaxyrus fowleri) congregated in the newly formed, sand flats and shallow, de‐vegetated pools resulting from the washouts. Neither ranid frogs nor Fowler's toads demonstrated avoidance of the sites affected by the herbicide treatment and mechanical rollover of the common reed. This evidence of species sorting, which enables multiple species to persist in a dynamic and heterogeneous landscape, suggests that wildlife management in aid of threatened species recovery may find success by encouraging natural disturbance regimes in dynamic landscapes. Future management endeavors should consider refraining from complete dune stabilization in these landscapes to allow the natural washouts to occur at a higher frequency, while ensuring the continued effectiveness of the invasive common reed eradication.

Centrifuge modelling on seismic failure of MSW landfills with high water level

Landfill failure threatens the safety of surrounding cities and causes soil and water pollution. High water levels can usually spur landfill failure. With the presence of earthquake, landfill instability is triggered in a greater possibility. However, the dynamic response and failure mechanism of landfills with high water level subjected to earthquakes are not yet clearly understood, and relevant experimental studies are quite scarce. This study includes a series of seismic centrifuge tests to investigate the seismic response of the landfill at different water levels. An improved method is proposed to prepare synthetic municipal solid wastes (MSWs) with similar static-dynamic properties to the actual MSWs. The failure and evolution mechanism of landfills with high water levels induced by the earthquake is revealed. Significant transitions are observed in the dynamic response of deformation, acceleration, and pore-water pressure as the water level changes. With the rise of water level, the settlement at the top of the landfill decreases first and then increases, while the horizontal displacement at the toe increases slowly, followed by a sudden drop; the acceleration amplification coefficient in the middle of the landfill increases first and then decreases; the dynamic pore-water pressure gradually decreases from positive to negative, but oscillates at the moderate water level. Three failure criteria and a hydro-earthquake coupled failure limit are proposed to demonstrate the combined effect of water level and earthquake on landfill stability. The test results provide a basis to establish seismic failure standards for landfills with different water levels and guide the seismic instability design of landfills with high water level.