Influence Of Water Level Fluctuation Research Articles

Simplified approach for sizing surge tank in long-distance pipeline systems

The cross-sectional area of a surge tank (CAST) is a key factor for protecting pipelines from harm by hydraulic transients. However, for long-distance pipeline systems (LDPS), the water level fluctuations in the surge tank and valve closure water hammer normally share a coupling relationship. Traditionally, this coupling relationship renders difficulty in determining the CAST. This study focused on the influence of water level fluctuation and water hammer, and proposed a simplified approach for sizing surge tanks. First, a water hammer formula that considers the coupling effect was derived. Subsequently, formulae for sizing the CAST were deduced. Finally, a case study of an actual LDPS was conducted to verify the accuracy of the presented formulae. In addition, the calculation errors caused by the theoretical assumptions are discussed. The results indicate that the theoretical calculation values and time-domain simulation results match well, thereby demonstrating the great convenience of designing surge tanks.

Impact of Water Level Fluctuation on Microplastic Transportation and Redistribution in a Floodplain Lake System

Microplastic contamination is a challenge in aquatic systems. Among these, floodplains exhibit their cyclical hydrological patterns with substantial fluctuations in water levels caused by annual floods or discharges from rivers into lakes. The influence of water level fluctuation on microplastics within complex floodplain systems has received limited attention in existing studies. This study employs hydrological data and a physics-based hydrodynamic model to assess the effects of water level fluctuations on the transport and redistribution of microplastics within Poyang Lake from 2018 to 2025. High spatiotemporal distribution variability in microplastic concentrations was found within the flood and drought periods. Furthermore, the residence rate of microplastics was assessed based on the microplastic concentration variations in the computational time. A gradual drop in the average discharge rate of microplastics was assessed at the outlet of Poyang Lake. The microplastics are more likely to drain into the Yangtze River in the high water-level period. Meanwhile, under the influence of hydrodynamics, local topography, and water level fluctuation, an accumulation of microplastics appears on the shallow shoals of the western and eastern regions of Poyang Lake, especially in the Gan River. Overall, by means of numerical simulation, the aim of our study is to serve as a reference and advance our understanding of the transportation patterns of microplastics at the aquatic–terrestrial interface.

Spatiotemporal distribution of phosphorus fractions and the potential release risks in sediments in a Yangtze River connected lake: new insights into the influence of water-level fluctuation

Spatiotemporal distribution of phosphorus fractions and the potential release risks in sediments in a Yangtze River connected lake: new insights into the influence of water-level fluctuation

The Influence of Water-Level Fluctuation on the Instability and Seepage Failure of Dump-Fill Cofferdam

Due to the double disturbance effect of dredging and filling, there will be a problem with weir slope stability after the formation of a fill type saturated clay weir. In order to study the influence of water-level fluctuation on the instability and seepage failure of the dump-fill cofferdam, the saturated-unsaturated seepage theory and strength reduction method are embedded into the finite element system such that the fluid-solid coupling stability of the dump-fill cofferdam is analyzed. The results show that the influence of water-level fluctuation on the instability and seepage failure of the dump-fill cofferdam can be revealed by the coupling analysis excellently. The variation of the saturation line of the cofferdam is consistent with the variation of water-level rising, but the change response of the saturation line of the cofferdam has a lag property during the water-level decline process in that the water level changes faster. The maximum displacement of the cofferdam can be approximated as two stages, namely, the stable growth stage and the accelerated growth stage (slip initiation), in which the influence of the water-level fluctuation on the displacement of stable growth stage is more obvious. Based on the fluid-solid coupling analysis, the most dangerous sliding surface of the cofferdam is located at the position of the horse path, with a critical strength reduction coefficient of approximately 1.475. The possibility of seepage failure of the cofferdam will be increased if the water level exceeds the height of the impermeable wall.

Ecological Influences of Water-Level Fluctuation on Food Web Network

Seasonal water-level fluctuations may lead to changes in river nutrients, which causes corresponding changes in the trophic structure of an aquatic food web, and finally affects the whole ecosystem. In this study, we focused on the Ganjing River, a tributary of the Yangtze River, China. Common organisms were sampled and measured for carbon and nitrogen stable isotopes in the wet and dry seasons, respectively, and the relative contributions of different food sources were combined to construct the food web, so as to realize the influence of water-level fluctuation on aquatic food web. Our results showed that basal food sources for fish consumers were endogenous carbon sources such as POM, zooplankton and zoobenthos in the dry season, while high water level exposed fish to more diverse and abundant food sources, and the contribution proportions of exogenous carbon sources (e.g., terrestrial detritus) to consumers increased in the wet season. In parallel, the abundance and species diversity of fish were higher than those in the dry season. Most fish species had relatively higher trophic levels in the dry season compared to the wet season, because the increase in fish densities led to an increase in piscivores fish. The food web was composed of planktonic and benthic food chains in the dry season. During the wet season, the planktonic food chain was dominant, followed by the herbivorous food chain, and the benthic food chain was relatively less important. Therefore, water-level fluctuation may alter the trophic linkages within fish communities, which contributed to a more complex and interconnected food web. Moreover, as we expect, the stable isotope analysis food web was broadly in line with the gut content analysis food web.

The influence of water level fluctuation on the stability of landslide in the Three Gorges Reservoir

In order to study the influence of water level fluctuation on the stability of landslide in the Three Gorges Reservoir (TGR), Xigouwan landslide was selected to be a research object to analyze its deformation mechanism as the fluctuation of the reservoir water level. Based on the long-term field monitoring of landslide, the evolution law of the surface has been studied. Based on the numerical simulation used by FLAC3D, five different water levels of TGR operating conditions are set, and the plastic zone, the factor of safety, change of displacement, and the seepage characteristics of the landslide were obtained to analyze the influence of water level fluctuation on the stability of landslide.

Indirect effects of climate change on zinc cycling in sediments: The role of changing water levels.

Increased variability in lake and river water levels associated with changing climate could impact the fate and effects of metals in redox-sensitive sediments through the alteration of microbial communities and of acid-base and redox chemistry. The objective of the present study was to determine the influence of water level fluctuation on metal speciation in porewater and predict environmental risk to high-carbonate systems. Using experimental microcosms with sediments collected from 4 metal-contaminated coastal freshwater wetlands in Michigan, USA, we conducted water level fluctuation experiments. Porewater and sediment metals (Ca, Cu, Fe, Mg, Mn, Ni, Zn) and important metal binding phases (iron-oxide speciation, acid-volatile sulfide) were quantified. In a short-term drying (seiche) experiment, there were decreases in all porewater metals after inundation of saturated sediments. During a drought experiment, re-inundation of oxidized sediments increased porewater Cu, Zn, Mg, Ca for most sites. Porewater Zn increased after inundation to levels exceeding the US Environmental Protection Agency threshold for chronic toxicity. These data show that the dissolution of metal carbonates and metal sulfates contributes to metal release after re-flooding and indicate that we might expect increased ecological risk to organisms present in drought-sensitive regions where altered hydroperiods are likely to increase metal bioavailability. Environ Toxicol Chem 2017;36:2456-2464. © 2017 SETAC.

Study on Damage Evolution Law of Rock Mechanics Parameters Under Water-Rock Interaction

The open pit locating in Cangshang was closed in 2005 because the reusing of pumping water resulted in the cyclic change of slope water level. In order to study the influence of water level fluctuation on mechanics parameters of the slope rocks, two kinds of typical rocks are selected to have the uniaxial compression tests of different saturation-dehydration circulation. The damage evolution law of rock mechanics parameters under water-rock interaction is found, whose results show that the mechanical properties of rock are weakened obviously by the water-rock interaction. In addition, the stronger the water-rock interaction becomes, the more obvious the weakening phenomenon is. Due to the different sensitivity to various parameters of water-rock interaction, the extent of elastic modulus decrease is the largest and uniaxial anti-compressive strength takes the second place while Poisson's ratio is essentially constant. Moreover, the uniaxial compressive strength and modulus of elasticity present exponential distribution with times of saturation-dehydration circulation. With the increase of the saturationdehydration times, the damage value increases accordingly while the increment tends to zero. Generally, the rock mechanical properties are hardly affected by water-rock interaction in the latter period; there are differences among the damage degree of various qualities of rocks, the better the quality, the smaller the damage, and the less the times reaching 95% limit damage value.

Influence of water level fluctuation on groundwater solute content in a tropical south Indian region: a geochemical modelling approach

Groundwater levels in the Dharapuram region exhibited drastic seasonal changes. Hydrogeochemical analysis were performed on the groundwater samples collected during January (post-monsoon) and July (pre-monsoon) in 2009 to understand the chemical changes and related process encountered during the fluctuated water table. Dominant water type in the study area was Na–Cl with smaller contributions from Ca–Cl and mixed Ca–Mg-Cl type of water. Gibbs plot employed to differentiate the controlling mechanisms of hydrochemistry, which showed that rock-water interaction is the dominant process. However, bivariate plots identified silicate weathering is the major contributor to the rock weathering. Higher concentration of Cl in the groundwater is suggesting the anthropogenic sources to ionic chemistry. Precise examination of the hydrochemical changes with rise and fall in the water table showed three distinct behavior; the EC, increased with increasing water level (type 1), increased with decreasing water level (type 2) and no significant changes with WL fluctuation(type 3). Aqueous speciation modeling was carried out on representative samples. This shows that dissolution and deposition of the carbonate minerals, mixing of textile wastes and the irrigation return flow were the major processes prevailing in the study area. However, the changes in chemical kinetics encountered during seasonal water level fluctuation are also controlling the hydrogeochemistry of this hard rock terrain.

Growth and Development of <i>Cyperus papyrus</i> in a Tropical Wetland

Relative growth rate (RGR) is an important parameter in plant growth models. However, no field measurements of RGR have been made in Cyperus papyrus (papyrus) wetlands. In this study, the growth dynamics of aerial shoots were investigated in a tropical papyrus wetland. The aim was to estimate temporal changes in the growth rates, and also establish the effect of water level and temperature change on total culm number, culm recruitment and senescence. Dry weights of shoots during their life cycle were determined using a non-destructive method after establishment of relationship between culm diameter and dry weight. Measurements were made over period of seven months. During the course of the measurements, culm density significantly increased from 16.1 to 35.9 culms.m-2. There were significant changes in both culm recruitment and senescence. Maximum RGR of developing culms was 1.04 g g-1 d-1. Using a culm density of 27 per m-2, productivity range was 16.74 to 37.37 g m-2 d-1. There was an inverse and significant relationship between rate of change in leaf weight ratio (LWR) and RGR of the culms. In conclusion, RGR of the aerial shoot development was controlled by rate of change in LWR from 41 to 156 days of growth. There was a strong and negative influence of water level fluctuation on total culm density.

Performance of Soil-Root System of <i>Setaria viridis</i> Community in Soil Reinforcement and Slope Protection on the Water-Level-Fluctuation Belt in the Three Gorges Reservoir Region

The soil-root system formatted by plant roots and soil has a good effect in soil reinforcement and slope protection. Setaria viridis is a common species distributing in the three gorges reservoir region. In order to determine the performance of the species in soil reinforcement and slope protection and its variation characteristics on the water-level-fluctuation belt, we tested the tensile strength, anti-scouribility, anti-erodibility and shear resistance of the community soil-root systems. The results showed that the root system of S. viridis community grew better with the increase of altitude under the influence of water level fluctuation. The soil - root system of S. viridis community has an effect on soil reinforcement and slope protection. Its tensile strength of roots ranged from 60 to 90 Kpa/mm2,and its anti-scouribility enhancement coefficient, soil anti-erodibility enhancement coefficient and shear strength of soil-root system reached 0.15 to 0.90, 0.30 to 0.73, and 9 to 24 Kpa respectively. Its effects in soil reinforcement increased with the altitude increases. The correlation analysis indicated that the effects related significantly with root biomass. It is concluded that spatial changes of effects of soil-root systems in its soil reinforcement and slope protection might result from difference of root growth caused by water level fluctuation.

Water level fluctuation and sediment–water nutrient exchange in Great Lakes coastal wetlands

The influence of water level fluctuation on sediment–water nutrient exchange in coastal wetlands of Lakes Michigan and Huron was investigated using controlled, laboratory experiments. At each wetland, sediment cores were collected from 5 locations along a transect perpendicular to the shoreline, desiccated for 8weeks, and then re-wetted with original site water for 24h to simulate water level fluctuation. Soluble reactive phosphorus release declined exponentially along transects, with highest release rates from sediments collected at the ordinary high water mark (OHWM), and lowest rates from sediments underlying water >0.25m in depth. Nitrate exchange showed no obvious pattern in the Lake Michigan wetlands but nitrate was lost at all locations in the Lake Huron wetlands, suggesting denitrification. Ammonium was released at all sites, but with no obvious pattern along transects. Sulfate release was low at the OHWM locations and increased in a lakeward direction, plateauing by the 0.25m water depth.Based on phosphorus (P) release rates, we modeled water level scenarios based on climate change projections to estimate the effects of 3 different water level recessions and 1 water level increase on system-level P exchange. The impact of the P release could be ecologically significant in the localized area of release given the high P concentrations measured in the overlying water during sediment incubations (>500μg/L). The long-term ecological significance of sediment nutrient flux under fluctuating water levels deserves further attention.

Analysis of the Influence of Reservoir Water Level Fluctuation on Bank Slope Stability

AbstractRoads in mountainous areas are always built beside the reservoir. The water level changes when water is stored or discharged, and the change in water level influences slope stability. Based on a certain bank slope project, the influence of water level fluctuation, decreased velocity, soil permeability, and excess pore water pressure on slope stability is analyzed by calculating the flow field and strength reduction of Plaxis. When the soil condition follows a drained behavior, the safety of the slope becomes decrescent and then increscent with the increase or decrease of the reservoir water level. A special water level exists at which the safety factor of slope would be minimal. With the decrease in water level, the safety of the slope following an undrained behavior of the soil would decrease by 10%, in contrast to when the soil follows a drained behavior. The faster the decrease in water level or the smaller the permeability coefficient of the soil, the worse the stability of the slope becomes.

Spatio-temporal distribution of cell-bound and dissolved geosmin in Wahnbach Reservoir: Causes and potential odour nuisances in raw water

In many lakes and reservoirs, problems caused by off-flavours are known to be particularly associated with the occurrence of planktonic and benthic cyanobacteria. Frequently observed objectionable taste and odorous products of cyanobacteria are geosmin and 2-methylisoborneol. Investigations focused on the littoral zone of Wahnbach Reservoir (Germany) revealed that benthic cyanobacteria were present in this oligotrophic drinking water reservoir. Benthic cyanobacteria were found in the depth horizon between 1.75 m and 11 m, particularly on south-exposed slopes. This spatial distribution indicates a possible key role of the underwater light climate. Moreover, cell-bound and dissolved geosmin were detected in corresponding littoral samples. Both fractions were subjected to spatial and primarily temporal variations with maximum concentrations at the end of summer. However, a substantial lowering of the water level caused a diminution of cyanobacterial growth. Due to the drawdown of the water level concentrations of cell-bound geosmin and pigments (as a proxy of cyanobacterial biomass) were remarkably reduced, and dissolved geosmin was never detected during this phase. Except for the influence of water level fluctuation no other abiotic variables had a significant influence on pigment and geosmin concentrations. From geosmin concentrations detected in the littoral zone, the probability of serious episodes of odour events in the raw water of the Wahnbach Reservoir was estimated. Hence, the probability that the raw water was affected by geosmin was minor, which was supported by routine flavour profiles. Nevertheless, the study shows that odorous episodes caused by benthic cyanobacteria are likely to develop even in an oligotrophic lake or reservoir when these cyanobacteria, and consequently odorous production, proliferate. In principle, such a proliferation cannot be excluded as nutrients are available from the sediment pore water, and underwater light at the sediment surface in the sub-littoral is sufficiently high due to very low phytoplankton-induced turbidity under oligotrophic conditions. Thus, management-induced fluctuations of the water level seem to be the main control variable to generate light conditions at the sediment surface fluctuating in a given depth horizon faster than cyanobacteria can develop there.

Influence of water level fluctuation on phreatic line in silty soil model slope

The water level fluctuation may affect the phreatic line in the waterfront soil slopes. In order to investigate the influence, three slope models were made using the silty soil. Four testing schemes for rising water level and three for lowering water level were done. The testing results indicated that such factors as the horizontal distance from the piezometer tube to the intersection of the slope surface and water level, the saturated state of the soil mass, and the rate of the water level fluctuation, might affect the changing rate of the water table in the piezometer tube. The comparison of the results obtained from the present approach with [Zhang Y.-Y. and Hu, X.-W., 2007. Calculation of saturation line of groundwater under reservoir water table uniform rising. Hydrogeology and Engineering Geology, 2007(5): 46–49. (in Chinese)] indicated that the works of Zhang and Hu (2007) may overestimate the elevation of the phreatic line under uniform rising conditions. The comparison of the results from the present approach with [Zheng, Y.-R, Shi, W.-M., and Kong W.-X., 2004. Calculation of seepage forces and phreatic surface under drawdown conditions. Chinese Journal of Rock Mechanics and Engineering, 23(18): 3203-3210. (In Chinese)] indicated that the works of Zheng et al. (2004) might estimate reasonably the elevation of the phreatic line under uniform lowering conditions, but when the lowering rate of the water level is very large, the works of Zheng et al. (2004) may underestimate the phreatic line.

Influence of water level fluctuation on the spatial dynamic of the water chemistry at Lake Fertõ/Neusiedler See

Lake Fertõ/Neusiedler See is a steppe lake situated on the Hungarian-Austrian border with a surface area of 309 km 2. It is an extremely shallow lake with regulated outflow. 54% of the whole lake and 85% of the Hungarian part (75 km 2) is covered by reed. There are numerous reedless areas (inner ponds) of variable size within the reed belt, which is enmeshed with canals connecting the inner ponds with the open water areas. Fundamental differences were recorded in the water chemistry of the three water type areas, open water, canals and inner ponds. The degree of these differences is basically determined by the distance from the open water areas and the water level of the actual years. An extremely high, an average and an extremely low water level year was examined, in order to present the spatial and temporal differences in the water chemistry of the investigated water bodies. Differences due to the water level fluctuation between years in the three different water types are discussed on the basis of electrical conductivity, cation, and anion concentration changes of the water. Our results support the concept of high instability of Lake Fertõ and describe habitats with remarkable temporal and spatial variability. The high influence of water level on habitat conditions at different sites of the lake recommend a carefull water level regulation strategy.

Studies on the coastal environment in Lake Biwa. I. Species composition and distribution of submerged macrophytes

In summer of 1997, submerged macrophytes were investigated in 6, 354 quadrats (10 m × 2 m) along 104 transects covering the whole littoral zone of Lake Biwa by SCUBA diving to obtain a quantitative view of species composition and horizontal and vertical distributions of respective species. Twenty three species were found in this survey. The species with a high frequency were Potamogeton maackianus, Hydrilla verticillata and Elodea nuttallii. The vegetation was classified into four types by cluster analysis using values of similarity index among all transects. Four types were as follows: west and north (N1), north-east (N2), south-east (N3) in Northern Basin, and Southern Basin (S). N2 type had the largest vegetational cover, cover layer, number of species and diversity index, and N1 type the smallest number of species. Applying the principal component analysis for Northern and Southern Basins, the richness of vegetation could be reasonably ordinated by the first principal component. The groups of species growing in different environmental conditions (wave energy, water depth, transparency and grain size) were also interpreted by the second and third principal components.Scatter diagrams for water depth and grain size of submerged macrophyte species showed the characteristic of habitat conditions in each basin, indicating higher habitat diversity in Northern Basin than in Southern Basin. Differences in vertical distubution patterns of some species between the basins were discussed in relation to the growth form, interspecific competition and environmental change (eutrophication, etc.). Influence of water level fluctuation on submerged macrophyte species was also discussed in the context of a possible low-water level (B.S.L. -1.5 m) in the Lake Biwa Development Project.