High Water Levels Research Articles

Optimizing Water Level Management Strategies to Strengthen Reservoir Support for Bird’s Migration Network

Migratory waterbirds depend on a complex network of wetlands globally for their life cycles. However, habitat loss and degradation pose risks to these networks’ sustainability, potentially impacting wetland habitat availability. This study investigates the impact of water level changes in Beijing’s Miyun Reservoir on white-naped cranes’ (Antigone vipio) habitat use. We utilized satellite imagery from 2000–2021 and monthly data from 2018–2023 to observe changes in the reservoir’s water and land areas. Additionally, the study tracked 32 cranes using GSM-GPS loggers, yielding insights into their movement patterns and habitat preferences. Our findings emphasize the significant influence of reservoir water levels on habitat availability for these cranes. Notably, our results indicate that the decrease in suitable migratory bird habitats in the reservoir is primarily attributed to high-water level management strategies. This study highlights the necessity for balanced management of aquatic and terrestrial areas in reservoir ecosystems to preserve migratory waterbird habitats.

Threats to the Lower Section of the River after Fish Mortality in the Ecological Environment of the Oder River

This work presents a case study accompanied by an analysis of potential reasons for fish mortality in the lower Oder River during an ecological disaster in August 2022. Changes in physicochemical water quality indicators indicate that fish and benthic organism death was likely due to the creation of hypoxia. The research also highlighted the trophic threats to the studied Oder River section linked to the disaster. The disaster occurred in the upper and middle Oder River, extending to the lower stretch. A physicochemical analysis of water samples revealed that the fish and organism death in the estuarine section was mainly due to reduced dissolved oxygen, caused by the decomposition of organic matter from the upper river sections. This was reinforced by high temperatures and low water levels. The negative trophic consequences of the described ecological disaster for the lower section of the Oder River may be long-term. Over thirty years of monitoring showed threats of excess biogenic compounds, organic matter, and bacterial contamination. Despite decreasing nitrogen and phosphorus, significant phytoplankton blooms implied internal nutrient sources. Considering climate change and the poor trophic status, recurrent disasters and deteriorating conditions are anticipated. Mitigation requires continuous monitoring, limiting the nutrient input (especially phosphorus), and preparing for extreme events. Geotechnical methods in the lower river can improve oxygen levels and fish survival.

Salt intrusion length in well-mixed Moroccan estuaries during infrequent events: a simple empirical equation development

ABSTRACT Infrequent events, such as periodical total moon or sun eclipses can affect the water resources in the estuaries. The Super Blue Blood Moon on (31/01/2018) and Total Solar eclipse on (21/08/2017) were investigated. The Bouregreg and Sebou estuaries (Morocco) were selected as an example location due to the availability of field survey data during infrequent events; and during these events both estuaries are well-mixed. Results showed that during these phenomena, the gravitational pull on the ocean is strong, so the high water is at its highest point and the low water at its lowest point. Water level rise affects the hydrodynamic balance and can increase salt water intrusion into the river estuaries, causing many ecological problems. The paper also presents a straightforward empirical equation for estimating salt intrusion length during high water levels. This equation proves valuable in offering initial estimates of salt intrusion length (LHWS) in estuaries during infrequent events in Moroccan estuaries.

The hydrological regime of Taihu Lake under the influence of anthropogenic activities

Study regionThe Taihu Lake is located at the downstream of the Yangtze River, China, which serves various functions such as regional flood control, drought resistance, and drinking water for many vital cities in China such as Shanghai, Hangzhou and Suzhou. Since 1950 s, Taihu Lake has experienced three stages of anthropogenic management. Due to these managements, the natural hydrologic properties of Taihu Lake are gradually disappearing, and the Taihu Lake tends to become an artificially controlled lake. Study focusTo understand how anthropogenic activities have impacted the hydrological regime of Taihu Lake at different stages, this study has analyzed daily average water level of Taihu Lake for 70 years and daily average precipitation data of the Taihu Lake Basin for 60 years. And finally it reveals the natural and anthropogenic effects on trend, amplitude, period and extreme water level of Taihu Lake. New hydrological insights for the regionThe multi-year average water level of Taihu Lake witnesses an increment of 0.23 m, and the contribution from anthropogenic activities account for 34.78%. The maximum decrements of frequency of extreme high and low water level drops by 29.55% and 7.69% recently due to anthropogenic activities. The anthropogenic activities on the hydrological regime in Taihu Lake has become increasingly pronounced, and these hydrological changes are beneficial for basin flood control and water resources.

Human displacements from Tropical Cyclone Idai attributable to climate change

Abstract. Extreme weather events, such as tropical cyclones, often trigger population displacement. The frequency and intensity of tropical cyclones are affected by anthropogenic climate change. However, the effect of historical climate change on displacement risk has so far not been quantified. Here, we show how displacement can be partially attributed to climate change using the example of the 2019 Tropical Cyclone Idai in Mozambique. We estimate the population exposed to high water levels following Idai's landfall using a combination of a 2D hydrodynamical storm surge model and a flood depth estimation algorithm to determine inland flood depths from remote sensing images, factual (climate change) and counterfactual (no climate change) mean sea level, and maximum wind speed conditions. Our main estimates indicate that climate change has increased displacement risk from this event by approximately 12 600–14 900 additional displaced persons, corresponding to about 2.7 % to 3.2 % of the observed displacements. The isolated effect of wind speed intensification is double that of sea level rise. These results are subject to important uncertainties related to both data and modeling assumptions, and we perform multiple sensitivity experiments to assess the range of uncertainty where possible. Besides highlighting the significant effects on humanitarian conditions already imparted by climate change, our study provides a blueprint for event-based displacement attribution.

Valuing equity-linked annuities under high-water mark fee structure

This paper studies the valuation of equity-linked investment products embedded with a high-water mark (HWM) fee structure. Under the HWM fee structure, the insurance company charges threshold fees at a constant rate from the policyholder's account whenever the account value is lower than a pre-specified level, and levies HMW fees at another constant rate whenever the account is hitting new record highs that are higher than another pre-specified level. The dynamics of the logarithmic value of the policyholder's account, before fees, is assumed to follow either a two-sided jump-diffusion process with double exponential jumps, or a down-ward jump-diffusion process with exponential jumps. For the two-sided jump-diffusion model with HWM fees, using the Wiener–Hopf factorisation theorem and the duality lemma, we derive an explicit expression for its potential measure. For the down-ward jump-diffusion model with both threshold fees and HWM fees, we are facilitated with the excursion theory to derive an explicit expression of the potential measure. Using the above newly derived potential measures, we are able to obtain formulas for valuing the equity-linked annuity under the HWM fee structure. Finally, we illustrate our results with some numerical examples.

Water and mineral composition of the exudate resulting from scarification of pau-pombo trees by black-tufted marmosets

Black-tufted marmosets to obtain tree exudates for food often use Tapirira guianensis trees. Tree exudates are sources of calories, nutrients and water. In seasonal droughts, the high concentration of water in the exudates can be an immediate source for marmosets. One of the most important elements for the metabolism of marmosets is calcium, but it remains to be proven whether T. guianensis gum is rich in calcium. This study characterizes the water and mineral composition of the exudate that is consumed by black-tufted marmosets in urban forests in the Cerrado domain. Orifice and stem exudate samples were collected from eight scarified T. guianensis trees. The composition of the exudate was characterized using bromatological methods. The exudate was shown to have high levels of water and calcium, which are essential for the metabolism of marmosets. Due to its characteristics, T. guianensis may be an important tree species for the feeding ecology of marmosets and should be taken into consideration when making wildlife management plans in the Cerrado domain.

The Structure of the Zooplankton Communities in Sukhoe More Bay, Southeastern White Sea

This paper presents the results of our investigation of the zooplankton communities from Sukhoe More Bay, located in the southeastern part of Dvina Bay of the White Sea, in July−August, 2018. The species composition, quantitative characteristics and spatial distribution of zooplankton were studied. The zooplankton communities are composed of 34 species of hydrobionts. Copepods were the dominant group in the entire study area. The zooplankton communities were characterized by high quantitative indicators. Juvenile stages of copepods were a significant contribution to the formation of the total number of zoocenoses. During high water level, the abundance of zooplankton was 37 000 ind./m3, biomass, 0.6 g/m3 (wet weight). During low water level these parameters were 210 000 ind./m3 and 1.7 g/m3 (wet weight), respectively. The structure, abundance and spatial distribution of zooplankton in the bay are determined by the morphometric features of the reservoir (shallow water), the influence of a complex of environmental factors (temperature and salinity), as well as tidal phenomena.

Hamilton's Proactive Leak Detection Improves Infrastructure and Water Quality

Key TakeawaysHamilton, Ont., has an older, elaborate water distribution system, with high levels of nonrevenue water (NRW).The city was determined to reduce its NRW, so it conducted a leak detection pilot study to explore advanced technologies that could improve detection efforts.With a 95.6% accuracy rate from the pilot test results, the city implemented a full‐scale, proactive leak detection program.

CT and X-ray contrast agents: Current clinical challenges and the future of contrast.

Computed tomography (CT) is a powerful and widely used imaging technique in modern medicine. However, it often requires the use of contrast agents to visualize structures with similar radiographic density. Unfortunately, current clinical contrast agents (CAs) for CT have remained largely unchanged for decades and come with several significant drawbacks, including serious nephrotoxicity and short circulation half-lives. The next generation of CT radiocontrast agents should strive to be long-circulating, non-toxic, and non-immunogenic. Nanoparticle contrast agents have shown promise in recent years and are likely to comprise the majority of next-generation CT contrast agents. This review highlights the fundamental mechanism and background of X-ray and contrast agents. It also focuses on the challenges associated with current clinical contrast agents and provides a brief overview of potential future agents that are based on various materials such as lipids, polymers, dendrimers, metallic, and non-metallic inorganic nanoparticles (NPs). STATEMENT OF SIGNIFICANCE: We realized a need for clarification on a number of concerns related to the use of iodinated contrast material as debates regarding the safety of these agents with patients with kidney disease, shellfish allergies, and thyroid dysfunction remain ongoing in medical practice. This review was partially inspired by debates witnessed in medical practice regarding outdated misconceptions of contrast material that warrant clarification in translational and clinical arenas. Given that conversation around currently available agents is at somewhat of a high water mark, and nanoparticle research has now reached an unprecedented number of readers, we find that this review is timely and unique in the context of recent discussions in the field.

An Analysis of Rainfall Characteristics and Rainfall Flood Relationships in Cities along the Yangtze River Based on Machine Learning: A Case Study of Luzhou

Cities along rivers are threatened by floods and waterlogging, and the relationship between rainstorms and floods is complex. The temporal and spatial distributions of rainstorms directly affect flood characteristics. The location of the rainstorm center determines the flood peaks, volumes, and processes. In this study, machine learning algorithms were introduced to analyze the rain–flood relationship in Luzhou City, Sichuan Province, China. The spatial and temporal patterns of rainstorms in the region were classified and extracted, and flood characteristics generated by various types of rainstorms were analyzed. In the first type, the center of the rainstorm was in the upper reaches of the Tuojiang River, and the resulting flood caused negligible damage to Luzhou. In the second type, the center of the rainstorm occurred in the Yangtze River Basin. Continuously high water levels in the Yangtze River, combined with local rainfall, supported urban drainage. In the third type, the rainstorm center occurred in the upper reaches of the Yangtze and Tuojiang rivers. During the flooding, rainfall from Yangtze River and Tuojiang River moved towards Luzhou together. The movement of the rainstorm center was consistent with the flood routing direction of the Yangtze and Tuojiang rivers, both of which continued to have high water levels. The flood risk is extremely high in this case, making it the riskiest rainfall process requiring prevention.

Study on the mechanical properties of embankment soil under long-term immersion conditions

During flood season, embankments are often submerged in high water levels for extended periods, leading to deterioration in their soil mechanics performance and increasing the risk of slope instability and other hazards. In order to investigate the changes in mechanical properties of embankment slopes during long-term water immersion, direct shear tests were conducted. Scanning electron microscopy, chemical composition analysis, and laser particle size analysis were conducted on samples taken at different immersion periods. Clay samples were taken from the embankments at Jiangxinzhou in Nanjing, Jiangsu Province, China. Results showed the shear strength of the soil gradually decreases with the increase of immersion time, while the cohesive force and internal friction angle gradually decrease as well. This suggests that immersion has a softening effect on the shear strength of the soil. As the immersion time increases, the colloidal particles (soluble salt) rapidly dissolves, the microstructure of the soil is destroyed, and sticky particles increases, resulting in a change in the shear strength of the soil. The research results provide a basis for flood control and prevention of embankments immersed in high water levels for long periods during the flood season.

The Nelson inquest: Relevance of the Victorian Charter to the coronial function of preventing deaths in custody

The 2023 coronial inquest findings into the death of Aboriginal woman, Ms Veronica Nelson, in a Victorian prison represents a high-water mark for the relevance and application of the Victorian Charter of Human Rights and Responsibilities Act 2006 to inquests into deaths in custody. The reliance on the Victorian Charter in the inquest was particularly significant because of the detailed findings and recommendations, directed at a wide variety of criminal justice system agencies, intended to prevent future deaths in custody. The outcome of the inquest clearly demonstrates that Human Rights Acts can enhance the preventive function of coroners in Australia.

Sedimentary facies and chronological study for a Late Pleistocene sand layer with swash cross bedding within a sand hill at north of Poyang Lake, as inferred from sedimentary structure and optical dating of K-feldspar and quartz grains

Poyang Lake is the largest freshwater lake in China. Currently, there are several sand hills around Poyang Lake and they were mainly interpreted to be formed by aeolian process. However, by field investigation, it is found that several sand/silt layers with parallel bedding, horizontal bedding and swash cross bedding were preserved within sand hills around Poyang Lake. Compared with recent highest water level in Poyang Lake since 1949, the sand/silt layers with parallel bedding, horizontal bedding and swash cross bedding are higher than 22.63m from several meters to more than 10 m. From the view of sedimentary structure, the sand/silt layers mentioned above should be treated as water-lain sediments. In this study, one sand layer with swash cross bedding at elevation of ∼47.5m within a sand hill at north of Poyang Lake was targeted. The bleaching of K-feldspar IRSL signals and quartz OSL signals during their deposition were further investigated by using optical dating techniques. It is found that both K-feldspar IRSL signals and quartz OSL signals were partially bleached and such phenomenon is very different from typical aeolian sediments. The partially bleaching of both K-feldspar IRSL signals and quartz OSL signals is consistent with interpretations by sedimentary structure of the targeted sand layer, i.e. the sand layer with the swash cross bedding within the sand hill should be interpreted as hydraulic sediments and they were not formed by aeolian process. The OSL ages of targeted sand layer were then analyzed by three different methods, i.e. single aliquot MET-pIRIR dating of K-feldspar, single aliquot OSL dating of quartz as well as single grain OSL dating of quartz. The OSL ages of three methods were all consistent with each other and the age results show that the targeted sand layer was formed during MIS 3a. Although previous studies suggested that previous Poyang Lake (Pengli Ze) was initially formed during mid-Holocene, our study indicates that previous Poyang Lake (Pengli Ze) already existed during MIS 3a and it might experience extremely high water level phase at that time.

Early-Middle Holocene high lake levels of Rinqen Shubtso on the southern Tibetan Plateau and the formation mechanisms

The lake-level highstands on the southern Tibetan Plateau (TP) during the Early-Middle Holocene have traditionally been attributed to increased monsoonal precipitation. However, there has been limited discussion and evaluation regarding how the elevated shoreline indicates the formation of mega-paleolakes and the effects of glacial meltwater on rising lake levels. In this study, we conducted an investigation into the well-preserved paleoshorelines of Rinqen Shubtso, a closed-basin lake system located on the southern TP. By utilizing 14C dating and analyzing shoreline elevations, the Holocene lake-level fluctuation history of Rinqen Shubtso was reconstructed. Through examining strontium (87Sr/86Sr) and oxygen isotopes (δ18O), as well as Rb/Sr ratios in tufa samples from the shoreline, we evaluated the relative contribution of glacial meltwater and East Asian Monsoon precipitation to the lake-level expansion throughout this period. Our findings indicate that prior to 8.5 cal ka BP, the lake level reached its highest elevation before experiencing a rapid drop by approximately 44 m within a short timeframe. Subsequently, maintaining a stable highstand between 8.5 and 5.8 cal ka BP before gradually declining to its present elevation thereafter. We argue that the glacial meltwater induced by rising temperature due to solar insolation likely played a significant role in contributing to these large amplitude high lake levels prior to 8.5 cal ka BP, whereas the maximum East Asian Monsoon precipitation was responsible for sustaining high water levels during 8.5–5.8 cal ka BP when the mean latitudinal position of the summer Intertropical Convergence Zone shifted northward until reached its northernmost point at 8.5 cal ka BP. Following 5.8 cal ka BP, with the weakening of summer monsoon precipitation observed, gradually decreased lake level occurred accordingly. Our results provide valuable insights into understanding past changes in lake level, which are of great importance to predicting future lake variations on the TP.

Improving Adaptive Capacity of Riverine Communities in Responding to Floods in Beledweyne District, Somalia

This study aimed at improving the adaptive capacity of riverine communities in responding to floods in Beledweyne district, Somalia. The objectives of the study were to examine the factors that determine flood vulnerability of riverine communities in responding to floods in Beledweyne District, Somalia, to assess the indicators of adaptive capacity of riverine communities in responding to floods in Beledweyne District, Somalia and to evaluate the adopted strategies for improving adaptive capacities to flood hazards by riverine communities of Beledweyne District, Somalia. The study employed quantitative research approach using descriptive research design to analyse the adaptive capacity of riverine communities in responding to floods in Beledweyne District, Somalia. The research used data collection tools like questionnaire, interview and documentary review to collect the data. The main findings of the study were that there are many factors determining flood vulnerability of riverine communities in responding to floods in Beledweyne District, Somalia like staying very close to the river increases community members’ vulnerability to floods in the areas, staying near the estuary to flood, staying near the high-water mark, staying near the river defense walls, staying near the basin bridge with poor condition and many others. Secondly, the findings of the study indicate that there are indicators of adaptive capacity of riverine communities in responding to floods in Beledweyne District, Somalia which they encompass: low level of emergency and preparedness plan and resources, low level of emergency and preparedness plan and resources, low improvement of livelihoods and rural economy in the flood prone areas and low improvement of livelihoods and rural economy in the flood prone areas. Furthermore, the findings of the study indicate that the recommend strategies for improving adaptive capacities to flood hazards by riverine communities of Beledweyne District, Somalia entail: continuous assessment of the sector and infrastructure vulnerability in the riverine communities, executing early actions to increase economic resilience in livelihoods, assessment of the critical infrastructure (roads, bridges, utilities, prevention of ad hoc basin defenses, favor non-structural solutions and preparation and implementation of effective early warning messages that reach marginalized groups of people. The study recommends that there should be preparation of medium-term development and spatial plans, there should be proper preparation of medium-term development and spatial plans in Beledweyne district, preparation of proper local plans and the district authority or leaders in collaboration with the national leaders should prepare proper local plans for riverine communities.

Influence of large reservoir operation on change patterns of fish community assembly and growth adaption at low and high-water levels

The Three Gorges Dam is the largest water conservancy project in the world, and the Three Gorges Reservoir Area (TGRA) possesses precious fish resources. Currently, due to the lack of efficient biodiversity monitoring tools, the precise evaluation of fish community composition in a riverine reservoir has been restricted. Here, we investigated fish resources using 12S-rDNA barcoding in the TGRA before and after 175 m water level during the first year of a 10-year Yangtze fishing ban. Our results showed that the fish composition exhibited obvious seasonal differences. The environmental water levels, land use, and spatial characteristics less influenced the development of fish communities. Based on Infer Community Assembly Mechanisms (iCAMP) by phylogenetic bin-based null model analysis, 66.12 % of unexplained variables were driven by stochastic processes of community assembly and unmeasured key factors. We developed a growth-limiting index (GLI) and firstly applied it to inferring fish environmental adaptability, revealing the growth adaption response of reservoir fish species to environmental pressure. Compared to the downstream from the dam, fish population growth at the low- or high-water levels was partly inhibited. However, seven species of tiny or medium-sized fish showed strong adaptability in the reservoir region at both water levels. Taken together, this study clarified the patterns of fish community assembly in the TGRA and provided unique insights for chronic monitoring of fish diversities in a reservoir.

Dike risk evaluation incorporating the contribution of coastal wetlands: A case study on Chongming Island, China

Due to the increasing risk of coastal disasters and climate change, the traditional gray sea dikes may become unsustainable. Coastal wetlands provide natural protection for shoreline areas and have wave attenuation capacities as green dikes. In this study, we developed a new assessment approach to evaluate comprehensive dike risk for coastal gray-green defense systems, based on the dike characters and the wave attenuation capacity of coastal wetlands for the Chongming Island. The risk assessment system consists of nine indicators of dike constructure standards, dike-top height, land subsidence, wetland vegetation width, wave attenuation capacity of vegetation, mean high water level, storm frequency, rain intensity, and annual rainfall, to determine the dike risk index (RI). The information of dike and meteorological conditions were obtained by carrying out a field survey and referring to construction bulletins and domestic statistical yearbooks. The wave attenuation effect of wetland vegetation was characterized by plant morphology and seasonality. The results indicated that, without the coastal wetland indicators, the RI values of most parts of the dike ring of the island were high. The high-risk regions were mainly located in the south and north shores, consisting of several old dikes that did not meet the constructure standard. The risk level was higher in summer and autumn than in winter and spring, due to seasonal variations (typhoon or storm frequency and intensity). When the coastal wetland indicators were included, the presence of coastal wetland vegetation reduced the dike RI values by an average of 13.6% around the Chongming Island. During the flourishing periods of the vegetation, a high rate of wave attenuation reduced the RI levels considerably. We provide a reliable framework to carry out large-scale and high-resolution dike risk assessment to be applied for wetland vegetation restoration, green dike construction, and risk management in coastal areas.

Modelling reservoir sediment flushing through a bottom tunnel with an initially covered intake

Sediment flushing through a bottom tunnel is one of the most effective methods to alleviate reservoir sedimentation. However, the multi-physical hydro-sediment-morphological processes of reservoir sediment flushing through an initially covered bottom tunnel intake have remained poorly understood, and a physically enhanced and practically viable mathematical model is required. The present study uses an integrated model to resolve sediment flushing through an initially covered bottom tunnel intake. The proposed model couples a two-dimensional double layer-averaged model for the reservoir with a one-dimensional model for the bottom tunnel by means of numerical fluxes calculations at the inner boundary. The governing equations are solved synchronously using a well-balanced finite volume method. Several parameters related to boundary resistances and sediment exchange flux need to be determined for model closure. The model is tested against data from a series of physical experiments on reservoir sediment flushing, with sound agreement achieved between computed and measured scour hole geometries. Moreover, the present model successfully predicts the occurrence of tunnel blockage. The results prove that reservoir sediment flushing is best accomplished for high reservoir water level, small cover layer thickness, short tunnel length and steep tunnel slope. The present model facilitates reservoir design and operation to help preserve reservoir capacity.

Larval plastic responses to warming and desiccation delay gonadal maturation in postmetamorphic spadefoot toads.

Developmental plasticity allows organisms to adjust life-history traits to varying environmental conditions, which can have concomitant effects across life stages. Many amphibians are suitable model systems to study plasticity because their larvae can adjust growth and differentiation under fluctuating environments. It is unknown, however, whether somatic and gonadal differentiation are equally affected by environmentally induced plasticity or whether their decoupling alters gonadal maturation postmetamorphosis, which may affect fitness. We tested if developmental acceleration in response to warming and desiccation risk results in shifts in gonadal maturation during metamorphosis and postmetamorphic growth in western spadefoot toads (Pelobates cultripes). We found additive effects of increased temperature and desiccation risk on development and growth at metamorphosis, which largely constrained gonadal maturation in metamorphic and postmetamorphic individuals of both sexes. Furthermore, the conditions experienced by larvae incurred sex-specific carryover effects on the gonadal maturation of juveniles 5 months after metamorphosis. In females, high temperature delayed ovarian maturation regardless of the water level. In males, exposure to high temperature and high water levels slightly delayed the testes' maturation. These results highlight the relevance of larval plasticity in the gonadal maturation of species undergoing metamorphosis, which may have implications for population demographics and the evolution of life histories.