High Water Levels Research Articles

Microbial community diversity and potential functionality in response to dam construction along the Three Gorge Reservoir, China.

River and reservoir bacterial communities are the most basic part of river biomes and ecosystem structure, and play an important role in river biological processes. Yet, it remains unclear how highly regulated dam reservoirs affect both soil and sediment bacterial communities. A temporal distribution pattern of bacterial communities was investigated using Illumina MiSeq sequencing in a transition section of the Three Gorges Reservoir (TGR). In total, 106,682 features belong to the bacteria kingdom, encompassing 95 phyla, 228 classes, 514 orders, 871 families, 1959 genera, and 3,053 species. With water level regulation, Shannon diversity index, and observed species differed significantly, with no significant difference in Simpson evenness. Both in the high water level period (October) and the low water level period (June), Proteobacteria, Acidobacteri, and Chloroflexi were the most abundant phyla. Whereas, based on PCA plots and Circos plot, the microbial community structure has changed significantly. LEfSe method was used to identify the classified bacterial taxa with significant abundance differences between the low water level and high water level periods. KOs (KEGG Orthology) pathway enrichment analysis were conducted to investigate functional and related metabolic pathways in groups. To some extent, it can be inferred that water level regulation affects community growth by affecting the metabolism of the microbial community.

Flow pattern formed over steps at a low-head dam: Salmon River Dam

ABSTRACT Building Stepping way over the low-head dams has been proposed to reduce the risk of drowning in submerged flow conditions. In the Salmon Barrier, adding two steps downstream of weir was previously suggested as an effective method for reducing the risk of drowning downstream of this dam. Given the effect of steps on the flow pattern downstream of the weir, the occurrence of dangerous submerged flows at different tailwaters was predicted, and the flow pattern expected at variable tailwaters was studied in comparison with the flow pattern passing over the sharp crested weir. According to the results, the submerged flow pattern downstream of the dam is a combination of the submerged flow pattern over the abrupt drop at low tailwaters and that over the sharp crested weir at high water levels. Consequently, similar correlations for predicting the flow regime downstream of these structures can be presented to predict the flow pattern at different tailwaters. The flow pattern over the step was compared with that over the abrupt drop, and a few diagrams were presented for predicting the occurrence of different flow patterns based on the submergence ratio of steps. Given the similarity of the flow pattern with those in the literature for sharp crested weirs, the flow pattern was also investigated at higher tailwaters. The comparison of correlations developed in this study indicated that the flow pattern approaches that reported in the literature for sharp crested weirs with increasing discharge.

Unraveling the 2021 Central Tennessee flood event using a hierarchical multi-model inundation modeling framework

Flood prediction systems need hierarchical atmospheric, hydrologic, and hydraulic models to predict rainfall, runoff, streamflow, and floodplain inundation. The accuracy of such systems depends on the error propagation through the modeling chain, sensitivity to input data, and choice of models. In this study, we used multiple precipitation forcings (hindcast and forecast) to drive hydrologic and hydrodynamic models to analyze the impacts of various drivers on the estimates of flood inundation depth and extent. We implement this framework to unravel the August 2021 extreme flooding event that occurred in Central Tennessee, USA. We used two radar-based quantitative precipitation estimates (STAGE4 and MRMS) as well as quantitative precipitation forecasts (QPF) from the National Weather Service Weather Prediction Center (WPC) to drive a series of models in the hierarchical framework, including the Variable Infiltration Capacity (VIC) land surface model, the Routing Application for Parallel Computation of Discharge (RAPID) river routing model, and the AutoRoute and TRITON inundation models. An evaluation with observed high-water marks demonstrates that the framework can reasonably simulate flood inundation. Despite the complex error propagation mechanism of the modeling chain, we show that inundation estimates are most sensitive to rainfall estimates. Most notably, QPF significantly underestimates flood magnitudes and inundations leading to unanticipated severe flooding for all stakeholders involved in the event. Finally, we discuss the implications of the hydrodynamic modeling framework for real-time flood forecasting.

COMPOUND URBAN COASTAL FLOOD MODELING: INTEGRATING TIDE, WAVES, PRECIPITATION AND HYDRAULIC INFRASTRUCTURE

Compound coastal flooding considers the joint impacts of marine and hydrologic interactions and has recently been identified as an international research priority. Along the US West Coast, winter storms often bring high marine water levels along with energetic waves and precipitation. Hydrodynamic models have been widely used to estimate flood impacts, including extreme estuarine water levels in compound events (e.g., riverine discharge-tide-storm surge interactions), and produced satisfactory results. However, few studies further consider overland flow routing and high-resolution flood mapping in highly urbanized, low-lying coastal areas. Here, an integrated Delft3D-FM based numerical modeling framework is used to explicitly resolve multi-pathway flood processes (i.e., high marine water levels, waves overtopping, precipitation) and infrastructure (e.g., seawalls, storm drains, artificial dunes).

Population Structure of European Whitefish Coregonus lavaretus (Salmonidae: Coregoninae) from the Lake–River System of the Subpolar Urals

This paper presents the first description of the population structure of sparsely rakered whitefish Coregonus lavaretus, which lives in the mountain lake–river system of the middle reaches of the Maly Patok River (a second order tributary of the Pechora River). It has been established that European whitefish has formed a complex system of local groups here, which are associated with small lakes of different types, located on the catchment area of this river. A relatively isolated whitefish lacustrine group, which differs in the pattern of the population dynamics and a rapid linear growth of individuals, has been formed in one of the water bodies. There is a temporary aggregation of whitefish in a small endorheic lake, which is recruited only in years with a very high water level during floods. The results of the study of the linear growth indicate the interrelationship between different groups of floodplain–river whitefish from the Maly Patok River basin.

Experimental investigations and three-dimensional computational fluid dynamics modeling of sediment transport in tanks influenced by cavities

Sediment transport is a very complex process in urban water systems, and sediment movement mechanisms are poorly understood. However, it is necessary to comprehend sediment transport to optimize stormwater and sewer tank designs for better performance in trapping particulate pollutants. This work focuses on the numerical simulation and experimental investigation of tank sediment transport. In the numerical simulation, a discrete phase model is applied to calculate particle trajectories, and the particle tracking calculation is coupled with the steady-state flow calculation. A user-defined function is developed in the Fluent computational fluid dynamics (CFD) code to implement the settling condition and improve the particle motion predictions. In the experimental work, a back-scattered ultrasonic method is used to measure the velocity field, and the accumulation of particles at the bottom is reproduced by transforming the raw experimental data. The sediment deposition is also recorded photographically, and the trap efficiency is calculated. The CFD and experimental results are compared to estimate the accuracy of the modified settling boundary condition, showing an improvement in the trap efficiency and deposition zone predictions. High water level in the tank corresponds to higher sediment trap efficiency, and sediment deposition type is strongly affected by the water level. Tank length and the presence of cavity alter the sediment deposition zone, and the presence of cavity increases the trap efficiency of tank.

ASSESSMENT OF WAVE-INDUCED MOMENTARY SEABED LIQUEFACTION

Seepage force induced by ocean waves has been related to the liquefaction around submarine structure, and it has been shown to cause significant sediment transport and rapid burial of pipelines and objects (Tsai et al., 2022). This study assesses the impact of momentary soil liquefaction due to pore pressure gradient near seabed generated by waves in the range of oceanic and coastal environment. The nonlinear wave solution of the stream function numerical approximation is applied to cover the wide range of wave condition in ocean and to evaluate the contribution of kinetic term in the energy equilibrium of water waves, which appears at least in third order analytical solution. The dispersion relation for coupled wave-soil interaction is discussed to shed insight on the effect of seabed response on wave dissipation. The present solution demonstrates the momentary liquefaction near mud line, which is triggered by the pore pressure gradient under wave trough and assesses the trigger criterion of wave condition in wave-current environment.

Changes in compound flood event frequency in northern and central Europe under climate change

The simultaneous occurrence of increased river discharge and high coastal water levels may cause compound flooding. Compound flood events can potentially cause greater damage than the separate occurrence of the underlying extreme events, making them essential for risk assessment. Even though a general increase in the frequency and/or severity of compound flood events is assumed due to climate change, there have been very few studies conducted for larger regions of Europe. Our work, therefore, focuses on the high-resolution analysis of changes in extreme events of coastal water levels, river discharge, and their concurrent appearance at the end of this century in northern and central Europe (2070–2099). For this, we analyze downscaled data sets from two global climate models (GCMs) for the two emissions scenarios RCP2.6 and RCP8.5. First, we compare the historical runs of the downscaled GCMs to historical reconstruction data to investigate if they deliver comparable results for northern and central Europe. Then we study changes in the intensity of extreme events, their number, and the duration of extreme event seasons under climate change. Our analysis shows increases in compound flood events over the whole European domain, mostly due to the rising mean sea level. In some areas, the number of compound flood event days increases by a factor of eight at the end of the current century. This increase is concomitant with an increase in the annual compound flood event season duration. Furthermore, the sea level rise associated with a global warming of 2K will result in double the amounts of compound flood event days for nearly every European river estuary considered.

An improved method for computing tidal datums

Tidal datums are reference water levels describing the characteristic periodic variations in sea surface elevation relative to a vertical datum at a particular location. There are two common approaches for computing tidal datums: 1) the harmonic constituent approach, and 2) the peaks approach. Using a new method based on the peaks approach, tidal datums were computed and compared with theoretically equivalent constituent-based datums for a global set of 206 coastal tide gauges. The peak-based method described herein identifies high and low water turning points and then systematically classifies each according to semidiurnal, diurnal, and spring tidal cycles. The classified peaks and troughs in both predicted (excluding non-astronomical influences) and observed water level time series were averaged over a 19-year period. Tidal datums, such as Mean High Water Springs and Mean Higher High Water, are relied upon by many coastal authorities to define the tidal component of coastal inundation thresholds. Differences of >20 cm were found across tidal regimes and continents, demonstrating that the peaks approach is preferable over the constituent approach where such differences are non-negligible. An open source Tide Peaks Toolbox for use in MATLAB is presented for computing peak-based datums from any high frequency water level observation record.

COASTAL DUNES CHANGES ALONG THE WESTERN COAST OF EUROPE

Coastal dunes are natural barriers buffering storm waves, protecting coastal communities from flooding and rising sea level, and providing a valuable source of biodiversity for the surrounding environment. Significant dune erosion caused by storm waves and high water levels generally takes place over hours or days, while post-storm recovery can take years or decades (Houser et al., 2015). Although coastal dunes have received quite a lot of attention over the last decades, knowledge gaps remain, and our understanding and predicting capacity of long-term (years to decades) coastal dune evolution remain limited. The large diversity of coastal dunes along the Atlantic coast of Europe and the sequence of extreme storms observed during the 2013/14 winter, considered as the most energetic storms since at least 1948 (Masselink, 2016), represent a unique opportunity to study the spectrum of coastal dune response and recovery from an extreme winter.

A GLOBAL CHARACTERISATION OF COASTAL REGIONS TO GUIDE NATURE-BASED SOLUTIONS TO SEA TURTLE NESTING BEACHES

Sea turtles are an important part of marine and coastal ecosystems around the world. Yet, six of seven sea turtle species are endangered (IUCN, 2021). While they spend most of their lives at sea, female turtles use sandy beaches as nesting habitat, where they dig their nests in the sand to incubate for up to two months. A major challenge to sea turtles is the degradation of their nesting beaches due to anthropogenic climate-change effects, such as accelerated sea level rise (SLR) and anomalous storm activity. While it is still uncertain how sandy beaches will respond to SLR, beaches backed by hard structures cannot migrate landward, leading to ‘coastal squeeze’—the erosion and consequential narrowing of beaches. Increased storm activity may lead to persistently high water levels at nesting beaches, resulting in the flooding or even erosion of incubating nests. Moreover, beach erosion during storms can bury nests under excessive sand and limit beach access through the formation of scarps. Nature-based solutions—for example in the form of turtle-friendly design of beaches along new land reclamations or by adding coastal vegetation or reefs to limit runup and reduce erosion on existing beaches—may offer promising opportunities to preserve and even expand global habitats for turtle nesting.

THE IMPACT OF EXTREME WATER LEVELS ON TORONTO ISLAND PARK AND INCREASING RESILIENCE AGAINST FUTURE FLOOD EVENTS

Toronto Island Park is a chain of fifteen low-lying islands in Lake Ontario located just south of the Toronto shoreline in Ontario, Canada. The Park serves as a popular year-round urban attraction of significant economic importance, and showcases unique natural features, cultural heritage, and sensitive ecosystems. The Park is home to Billy Bishop Airport, Centreville Amusement Park, numerous small businesses, and over 250 residential homes. In recent years, the Toronto Islands have suffered significant physical and economic impacts due to flooding caused by extreme wet weather and record high water levels on Lake Ontario. In 2021, Baird was retained by the Toronto and Region Conservation Authority (TRCA) to develop long-term flood and erosion mitigation concept alternatives to replace temporary and emergency measures and to increase the functionality and resilience of the flood control infrastructure on the islands. This abstract outlines the various concept alternatives that were considered, the public engagement process and resulting preferred concepts for flood mitigation.

SUITABLE BOUNDARY LOCATION IDENTIFCATION FOR RAINFALL-RUNOFF AND SURGE MODEL COUPLING TO EVALUATE COMPOUND FLOOD HAZARDS IN COASTAL REGIONS

Flooding in many coastal regions is exacerbated due to complex interactions of multiple flood drivers such as rainfall-runoff and coastal surge which can occur simultaneously or sequentially during storm events, leading to compound flooding hazards. The Texas Gulf Coasts (USA) are especially vulnerable from compound flooding due to frequent occurrence of tropical storms which bring strong winds to drive storm surge and heavy rainfall to generate inland flooding. Large scale studies {Coastal Texas Restoration and Protection Study (CTX, 2021), Texas General Land Office’s Texas River Basin Study, Base Level Engineering Study} are being conducted by state and federal agencies for flood hazard assessment and for development of mitigation and abatement strategies for reducing this risk and increasing community resilience. Traditionally, large scale storm surge models do not account for runoff contributions to water levels in the interior of their domain. Riverine models for their part use either normal depth or mean high water levels to assign downstream boundary conditions within tidally influenced area, thus ignoring effects of storm surge. In this Planning Assistance to States (PAS) study, located in the Lower Clear Creek and Dickinson Bayou watersheds (Texas, USA), we have evaluated rainfall-runoff and storm surge interactions to determine suitable locations to use as model boundary conditions for exchanging data between rainfall-runoff and surge models under compound flooding conditions.

Optimal investment under high-water mark contracts with model ambiguity

This paper incorporates the ambiguities of the risky asset and the exogenous shock to explore how the two ambiguities influence the hedge funds model. We find the ambiguity of the risky asset makes the manager more risk averse and invest less. While the ambiguity of the exogenous shock induce the manager adopt radical investment way and invest more. But at the lower and upper bounds, both ambiguities do not work any more. The manager’s total value is eroded by either of the two ambiguities. Although the manager adopts different investment strategies for the two ambiguities, her income makes little difference. In high uncertain context of the external shock or the risky asset, manager’s rigorous investment strategies can protect the values of the investors and the entire fund. Both of the ambiguities have negative influences on the incentive fee and also reduce the proportion of incentive fee in her total income.

Beach rebuilding period buffers Indiana beach erosion in Lake Michigan

Recent high-water levels in the Laurentian Great Lakes caused widespread shoreline damage to beaches, homes, and coastal infrastructure. To quantify these shoreline changes and place them in historical context, shoreline imagery was analyzed to determine the magnitude, rates, and spatial variability of shoreline changes along the Indiana shoreline of Lake Michigan. The analysis shows that over the recent period of water level increase from 2013 to 2020, during which the water level rose nearly 2 m, the median shoreline recession along the Indiana coastline was 58 m and the median recession slope was 35:1 (shoreline recession : water level change). This magnitude of shoreline change is comparable to that experienced in other water level increase periods, 1965–1973 and 1990–1998. This recent shoreline recession was highly variable spatially, but not strongly correlated with shoreline type or position relative to littoral barriers. In spite of the widespread recent shoreline changes, the 2020 shoreline was generally more lakeward than previous high-water shorelines examined, with the exception of historical erosion zones downdrift of littoral barriers. Analysis of water level records and available wave hindcasts for the coastline suggest that while large, the erosion associated with the recent water level increase was tempered by a prolonged beach rebuilding period of low water levels and waves that resulted in an accreted shoreline that largely buffered the erosion associated with the water level increase. These results suggest that recent Indiana erosion could have been substantially worse had it not been preceded by the beach rebuilding period.

Organophosphate esters (OPEs) in a heavily polluted river in South China: Occurrence, spatiotemporal trends, sources, and phase distribution

In the past decade, organophosphate esters (OPEs) undergo rapid increase in production and use. Meanwhile, owing to their additive property, OPEs exhibit liability to escape from related products and therefore ubiquity in various environments. Moreover, numerous researches verify their bioavailability and negative effects on biota and human, hence their occurrence and associated risks have caught much concern, particularly those in aquatic systems. So far, however, OPEs in water are generally investigated as a whole, their phase distribution and behavior in waterbodies are incompletely characterized. We examined 25 OPEs in water (including dissolved and particulate phases), sediment, and sediment core samples from the Lian River, which flows through the Guiyu e-waste recycling zone and Shantou specific economic zone in South China. Compared to most global waterbodies, the Lian River showed high or ultrahigh OPE levels in both water and sediments, particularly in the reaches surrounded by e-waste recycling and plastic-related industries, which were the top two greatest OPE sources. Non-industrial and agriculture-related anthropogenic activities also contributed OPEs. Sediment core data suggested that OPEs have been present in waters in Guiyu since the 1960s and showed a temporal trend consistent with the local waste-recycling business. The phase distribution of OPEs in the Lian River was significantly correlated with their hydrophobicity and solubility. Owing to their wide range of physicochemical properties, OPE congeners showed significant percentage differences in the Lian River water and sediments. Generally, OPEs in water reflect their dynamic real-time inputs, while those in sediment signify their accumulative deposition, which is another cause of their phase distribution disparities in the Lian River. The physicochemical parameters of OPEs first imposed negative and then positive influences on their dissolved phase-sediment distribution, indicating the involvement of both the adsorption of dissolved OPEs and the deposition of particle-bound OPEs.

Response of denitrification microbiome to the nitrogen flux in three Gorges reservoir (TGR) sediments during two seasonal water fluctuation events

Three Gorges Reservoir (TGR) water fluctuation creates high water level (HWL) and low water level (LWL) condition in TGR aquatic ecosystem. HWL fluies significant nutrients, mainly introducing carbon and nitrogen into the ecosystem. The nitrogen input is a concern for water quality management of TGR since the possible eutrophication caused by nitrogen spike. Sediment denitrification is widely recognized as the dominant nitrogen removal process in freshwater ecosystem. Therefore, the response of TGR sediments microbiome to the input nitrogen flucatution is crucial for both nitrogen balance and the eutrophication status of the ecosystem. Using high throughout sequencing of 16S rRNA gene and the predicted denitrification enzyme, and qualitative PCR of denitrification functional genes, we investigated how TGR sediments denitrification microbiome respond to the input nitrogen flux during two seasonal water fluctuation events. Concomitant to expected input carbon and nitrogen, we observed distinct microbial community structure and denitrification microbiota in HWL and LWL, and also in seasonal sampling events. Sediments pH, total nitrogen and nitrate were the significant impact factors in shaping the microbial community structure. Important denitrification microbiota (e.g., Saprospiraceae, Gemmatimonadaceae, Pseudomonas) are the main taxa of the microbial community and also showed water level and seasonal variation. The relative abundance of denitrification enzyme (nar, nir, nor, nos) and function genes (nirS, nirK, nosZ) were higher in LWL than HWL. Denitrification enzyme were significantly (p < 0.05) correlated with the nitrate concentration. In addition, the relative abundance of denitrification enzyme and function genes increased during the transition from 2014 HWL to 2015 LWL. Results suggested that TGR sediments denitrification is nitrate concentration dependent. The denitrification microbiome is initially inhibited due to high nitrate input, then they developed denitrification ability in response to high nitrate concentration.

Analisis Pola Aliran Air Tanah Di Sekitar Saluran Pembuang Pada Lahan Gambut Tropis Dengan Fungsi Lahan Pertanian

This study aims to analyze the pattern of groundwater flow around drains on tropical peatlands and to determine the effect of groundwater around drains on tropical peatlands with agricultural land functions. The research data used is primary data, namely water level, distance of each well pipe, coordinate points. In carrying out the analysis process using surfer software.The results showed that the pattern of groundwater flow around the drainage canal on tropical peatlands is that it tends to flow from the land to the drainage canal with the condition that the water level in the channel is lower than the groundwater level on the land.Besides that, from the results of the analysis carried out, it was found that the water level in the drain has an effect on the pattern of groundwater flow in tropical peatlands (agricultural land functions). The greater the difference in the height of the water level in the drainage canal (low water level condition), with the ground water level in the field (high water level condition), the pattern of groundwater flow tends to move towards the canal. However, when the water level in the channel is almost the same as the groundwater level in the field, the pattern of groundwater flow will change.

Assessment of UAS Photogrammetry and Planet Imagery for Monitoring Water Levels around Railway Tracks

High water levels near railway tracks can be a major factor affecting the safety of train passage. Water conditions near the tracks are normally monitored through visual inspections. However, this method is limited in spatial coverage and may not provide comparable information over time. We evaluated the utility of satellite imagery (Planet Dove constellation at 3 m pixel size) at the landscape level to assess overall water surface area along railway tracks. Comparatively, we evaluated the use of Structure- from-Motion 3D point clouds and high spatial detail orthomosaics (3 cm) generated from a commercial off-the-shelf Unmanned Aerial System (UAS) (DJI M300 RTK) for measuring vertical water level changes and extent of surface water, respectively, within the right-of-way of a railway line in Ontario, Canada, in areas prone to high water level and flooding. Test sites of varied lengths (~180 m to 500 m), were assessed four times between June and October 2021. Our results indicate that the satellite imagery provides a large-scale overview regarding the extent of open water in wetlands at long distances from the railway tracks. Analysis of the UAS derived 3D point cloud indicates that changes in water level can be determined at the centimeter scale. Furthermore, the spatial error (horizontal and vertical alignments) between the multi-temporal UAS data collections between sites was less than 3 cm. Our research highlights the importance of using consistent UAS data collection protocols, and the significant potential of commercial off-the-shelf UAS systems for water level monitoring along railway tracks.

Small Organisms in a Large River: What Provides the High Diversity of Scaled Chrysophytes in the Ob River?

Currents are one of the main factors favoring the dispersal of microscopic planktic organisms over inland lakes and rivers. Large rivers of the northern hemisphere, flowing from south to north, can increase the diversity of northern latitudes with boreal species, while high water levels and floods expand the range of ecotopes and the biodiversity of rivers. We studied the distribution of the taxonomic structure and species richness of scaled chrysophytes downstream of the Ob river—a large river in West Siberia—at the end of the high-water period (June). Methods of scanning and transmission microscopy allowed the determination of a high taxonomic richness of these organisms, 67 species in total. The species were unevenly distributed by stations, with the maximum number of species (54) occurring in a shallow still bay without current and with minimum turbidity and a small number of diatoms. The species diversity in the main current was represented mainly by ubiquitous and cosmopolitan species.Water level fall usually coincides with the end of the vegetation of many scaled chrysophytes and the formation of stomatocysts. The stomatocysts of different species may drift downstream and then germinate when they find suitable conditions at theappropriatetime. Large rivers that are subject to significant changes in water level during their hydrologicalperiodsare able to host ahigh diversity of microscopic planktic organisms. Studying this capacity may reinforce the hypothesis of an omnipresence, i.e., that “everything is everywhere”.