Changes In Water Flow Research Articles

Water chemistry in the microenvironment of rainbow trout Oncorhynchus mykiss embryos is affected by development, the egg capsule and crowding

The hypothesis tested was that embryonic metabolism affects the water chemistry in the boundary layer. In addition, embryo crowding would further compound the metabolic effect on the water chemistry in the boundary layer. As development progressed, the magnitude of the boundary layer gradients for O(2) and pH, but not for NH4(+), increased. The presence of the egg capsule hindered the diffusion of O(2) into and H(+) and NH4(+) out of the embryo. The magnitude of the O(2), pH and NH4(+) boundary layer gradient was significantly increased when embryos were surrounded by either sham embryos or live embryos. The majority of this crowding effect on embryo boundary layers was due to changes in water flow rather than due to metabolism directly. These results clearly show that the microenvironment adjacent to the developing rainbow trout Oncorhynchus mykiss embryo becomes more stagnant as development progresses in the presence of the egg capsule and is further intensified with embryo crowding.

Thermal shocks influence on the growth process and optical quality of Nd: YAG crystal

In this paper, the effect of two kinds of thermal shocks on the quality of Nd:YAG single crystal grown by Czochralski method have been investigated. The shocks induced by unexpected change in water flow of cooling system, have a drastic influence on the stability of growth process. This is the intensity and duration of the shocks that affect on the crystal quality as it is evaluated by parallel plane polariscope and Fizeau interferometer. The experimental findings indicate that the time duration of the shocks has more undesirable influence on the crystal quality than the intensity of shocks. Duration of the shocks could make the crystal not suited for laser applications.

Thermokarst lake, hydrological flow and water balance indicators of permafrost change in Western Siberia

Permafrost, mainly of discontinuous type, that underlies the tundra and taiga landscapes of the Nadym and Pur river basins in northwestern Siberia has been warming during the recent decades. A mosaic of thermokarst lakes and wetlands dominates this area. In this study we tested the hypothesis chain that permafrost thawing changes thermokarst lake area and number, and is then also reflected in and detectable through other associated hydrological changes. Based on indications from previous studies, the other hydrological changes in a basin were expected to be decreasing intra-annual runoff variability (quantified by decreasing maximum and increasing minimum runoff) and systematically decreasing water storage. To test this hypothesis chain, we mapped thermokarst lake changes using remote sensing analysis and analyzed both climate (temperature and precipitation) and water flow and balance changes using available monthly data records. This was done for the whole Nadym and Pur river basins and a smaller sub-basin of the former (denoted 7129) with comparable data availability as the whole river basins. The results for the 7129 sub-basin show all the indicators (thermokarst lake and other hydrological) changing consistently, as could be expected in response to permafrost thawing that alters the connections between surface and subsurface waters, and leads to overall decreases in water (including ground ice) storage within a basin. Over the Nadym and Pur basins, the relative area influenced by similar permafrost thawing and associated lake and hydrological effects appears (yet) too small to be clearly and systematically reflected in the basin-average indicators for these large basins.

Turbidity maxima in four macrotidal estuaries

Hydrodynamic and fine sediment transport characteristics of four major macrotidal Northern European estuaries are compared. The four estuaries (Weser, Seine, Scheldt, Humber) are amongst those key to navigation and shipping in that they are home to several major European ports (e.g. Hull, Antwerp, Le Havre). In particular, the characteristics and behaviour of the estuarine turbidity maximum are described for each system. While this is a complex topic that continues to benefit from ongoing research, some similarities exist between the estuaries in terms of the response of the turbidity maximum to changes in tidal range (during the neap–spring–neap cycle) and fresh water flow (due to seasonal variations in rainfall in the catchments). The hydrodynamics of the four estuaries are very similar, and are characterised by faster, shorter flood tide currents compared with longer, slower ebb tides. Under low fresh water flow conditions, the turbidity maximum is in each case moved upstream, while high fresh water flow conditions cause a net seaward movement of the turbidity maximum. While in general the concentrations of suspended sediment within turbidity maxima are no more than a few hundred milligrams per litre, the particular topography of the Humber estuary system leads to concentrations considerably higher than this.

Development and primary verification of a transient analysis software for high temperature gas-cooled reactor helium turbine power system

The transient analysis software, HTR-GTsim, is developed to simulate transient characteristics of a high temperature gas-cooled reactor helium turbine power system (HTR-10GT) of INET in Tsinghua University, which is the secondary engineering project of HTR-10. The analysis models include point reactor neutron kinetics model, one-dimensional thermodynamic reactor model, rotor dynamic blower model, counter-current heat exchanger model, quasi-static helium turbine and pressure compressor model, and so on. HTR-GTsim is verified by 3 tests of a 10MW high temperature gas-cooled reactor (HTR-10), which are reactivity insertion test, helium flow change test and water flow change test. The simulation results of reactivity insertion test show that there is a strong self-adjusting ability for HTR-10 reactor power due to negative temperature feedback. The simulation results of helium flow change test are compared with those of the water flow change test. It is found that the disturbance induced in the latter test is significantly weaker than that in the former due to the huge heat capacity of the graphite in the core. The calculation results of HTR-GTsim are compared with the test data and simulation results of THERMIX program. Good agreement is obtained. Because of the limitation of validation, more work need to be done to verify the accuracy of HTR-GTsim to simulate a gas turbine device.

Putting the “Ecology” into Environmental Flows: Ecological Dynamics and Demographic Modelling

There have been significant diversions of water from rivers and streams around the world; natural flow regimes have been perturbed by dams, barriers and excessive extractions. Many aspects of the ecological 'health' of riverine systems have declined due to changes in water flows, which has stimulated the development of thinking about the maintenance and restoration of these systems, which we refer to as environmental flow methodologies (EFMs). Most existing EFMs cannot deliver information on the population viability of species because they: (1) use habitat suitability as a proxy for population status; (2) use historical time series (usually of short duration) to forecast future conditions and flow sequences; (3) cannot, or do not, handle extreme flow events associated with climate variability; and (4) assume process stationarity for flow sequences, which means the past sequences are treated as good indicators of the future. These assumptions undermine the capacity of EFMs to properly represent risks associated with different flow management options; assumption (4) is untenable given most climate-change predictions. We discuss these concerns and advocate the use of demographic modelling as a more appropriate tool for linking population dynamics to flow regime change. A 'meta-species' approach to demographic modelling is discussed as a useful step from habitat based models towards modelling strategies grounded in ecological theory when limited data are available on flow-demographic relationships. Data requirements of demographic models will undoubtedly expose gaps in existing knowledge, but, in so doing, will strengthen future efforts to link changes in river flows with their ecological consequences.

L자형 이동상수로에서 댐 붕괴파의 수치해석

We conducted a three-dimensional numerical simulation by using the FLOW-3D, with RANS as the governing equation, in an effort to track the dam-break wave.immediately after a dam break.in areas surrounding where the dam break took place as well as the bed change caused by the dam-break wave. In particular, we computed the bed change in the movable bed and compared the variation in flood wave induced by the bed change with our analysis results in the fixed bed. The analysis results can be summarized as follows: First, the analysis results on the flood wave in the L-shaped channel and on the flood wave and bed change in the movable-bed channel successfully reproduce the findings of the hydraulic experiment. Second, the concentration of suspended sediment is the highest in the front of the flood wave, and the greatest bed change is observed in the direct downstream of the dam where the water flow changes tremendously. Generated in the upstream of the channel, suspended sediment results in erosion and sedimentation alternately in the downstream region. With the arrival of the flood wave, erosion initially prove predominant in the inner side of the L-shaped bend, but over time, it tends to move gradually toward the outer side of the bend. Third, the flood wave in the L-shaped channel with a movable bed propagates at a slower pace than that in the fixed bed due to the erosion and sedimentation of the bed, leading to a remarkable increase in flood water level.

Ant Colony Algorithm Application in Water Treatment Control System Parameter Tuning

In Thermal Power Generation and heating Water Treatment process, duo to the water supply pipeline pressure and flow changes, the traditional PID control system controller cannot the prompt track response, PH value of water changes in a larger range, increased damage to the boiler pipes. In order to solve the problem which the control parameters optimizes, improves the system performance, proposed a new Ant colony algorithm PID parameters optimization strategy, this solution can combine characteristics that Ant colony algorithm can fast find the most superior parameter solution stably and PID can precise adjustment. In the control process, taken the PID parameters as a colony of ants, used to control the absolute error integral function as the optimization objective, dynamically adjust the PID control parameters in the control process, so as to realize the PID parameters on-line tuning, to improve real-time of the water treatment control system, improved the stability of the system, and achieve a better control effect.

Inside and Outside Earth Pressure Research of Steel Sheet Pile Cofferdam

As the cofferdam makes the water flow change, the river bed near the cofferdam has been washed; soil pressure on the cofferdam will be changed. In order to better grasp the force of the cofferdam, the earth pressure on the cofferdam need to be monitored. As it is difficult to monitor occasion, the computing earth pressure is necessary. In this paper, three-dimensional finite element model on the steel sheet pile, purlin, internal support and soil can be established. Through compassion computing value of model and monitoring value, conclusions are drawn.

Inside and Outside Earth Pressure Research of Steel Sheet Pile Cofferdam

As the cofferdam makes the water flow change, the river bed near the cofferdam has been washed; soil pressure on the cofferdam will be changed. In order to better grasp the force of the cofferdam, the earth pressure on the cofferdam need to be monitored. As it is difficult to monitor occasion, the computing earth pressure is necessary. In this paper, three-dimensional finite element model on the steel sheet pile, purlin, internal support and soil can be established. Through compassion computing value of model and monitoring value, conclusions are drawn.

Mathematical model to identify nitrogen variability in large rivers

AbstractThe river Swale in Yorkshire, northern England has been the subject of many studies concerning water quality. This paper builds on existing data resources and previous 1D river water quality modelling applications at daily resolution (using QUESTOR) to provide a different perspective on understanding pollution, through simulation of the short‐term dynamics of nutrient transport along the river. The two main objectives are (1) building, calibration and evaluation of a detailed mathematical model (Advection‐Dispersion Model: ADModel), for nutrient transport under unsteady flow conditions and (2) the development of methods for estimating key parameters characterizing pollutant transport (velocity, dispersion coefficient and transformation rates) as functions of hydrological parameters and/or seasonality.The study of ammonium and nitrate has highlighted temporal variability in processes, with maximum nitrification and denitrification rates during autumn. Results show that ADModel is able to predict the main trend of measured concentration with reasonable accuracy and accounts for temporal changes in water flow and pollutant load along the river. Prediction accuracy could be improved through more detailed modelling of transformation processes by taking into account the variability of factors for which existing data were insufficient to allow representation. For example, modelling indicates that interactions with bed sediment may provide an additional source of nutrients during high spring flows. Copyright © 2010 John Wiley & Sons, Ltd.

Functional characteristics of traps of aquatic carnivorous Utricularia species

Firing and resetting of traps in aquatic Utricularia species are associated with water flow and trap volume changes. In this study, trap thickness was used as a measure of water flow and was monitored automatically using an electronic position sensor. The basic characteristics of mechanically stimulated firing and resetting were measured in isolated traps from 13 aquatic Utricularia species and in two trap size categories in Utricularia reflexa. This allowed to study the relationship between these trap functions and trap thickness and length (criteria of trap size). Additionally, the characteristics of spontaneous firings (without any mechanical stimulation) were compared for U. reflexa traps fed or denied prey during a 1-day period. On the absolute scale, the 13 Utricularia species differed considerably in their firing and resetting rates. Significant interspecific differences were also found in the magnitude of firing (in total 3.7–4.2 times) and resetting rates (10–24 times) per unit trap thickness or length. Overall, traps of Utricularia australis, Utricularia stellaris and Utricularia inflata showed the greatest firing and resetting rates. The relative magnitude of firing per unit trap thickness or length showed a highly significant negative correlation with both trap thickness and length and the same also held for the relative resetting rates. Smaller and narrower traps are thus relatively more effective at trap firing and resetting than larger traps. Neither firing nor resetting characteristics were significantly different between unfed and prey-fed traps of U. reflexa and this was also true for the occurrence of spontaneous firings. A strict linear resetting rate, without any lag-period, was found during the first 3 min after trap firing in U. reflexa. This suggests that water is pumped out of the trap continuously and probably recirculates. Given the concepts of spontaneous firing and water recirculation, an ecological model based on the literature data has been devised to quantify the daily N and P gain from the ambient water by Utricularia traps devoid of animal prey. The model shows that the total N and P content estimated in the trap fluid is too high to be accumulated from only the ambient water. This implies that the prey-free traps do not take up N or P from the trap fluid but rather exude a quantity of these nutrients to the fluid to support the microbial community. Therefore, the trap microorganisms behave more as parasites than commensals and represent an additional ecological cost for trap maintenance.

A tidal creek water budget: Estimation of groundwater discharge and overland flow using hydrologic modeling in the Southern Everglades

Taylor Slough is one of the natural freshwater contributors to Florida Bay through a network of microtidal creeks crossing the Everglades Mangrove Ecotone Region (EMER). The EMER ecological function is critical since it mediates freshwater and nutrient inputs and controls the water quality in Eastern Florida Bay. Furthermore, this region is vulnerable to changing hydrodynamics and nutrient loadings as a result of upstream freshwater management practices proposed by the Comprehensive Everglades Restoration Program (CERP), currently the largest wetland restoration project in the USA. Despite the hydrological importance of Taylor Slough in the water budget of Florida Bay, there are no fine scale (∼1 km 2) hydrodynamic models of this system that can be utilized as a tool to evaluate potential changes in water flow, salinity, and water quality. Taylor River is one of the major creeks draining Taylor Slough freshwater into Florida Bay. We performed a water budget analysis for the Taylor River area, based on long-term hydrologic data (1999–2007) and supplemented by hydrodynamic modeling using a MIKE FLOOD (DHI, http://dhigroup.com/) model to evaluate groundwater and overland water discharges. The seasonal hydrologic characteristics are very distinctive (average Taylor River wet vs. dry season outflow was 6 to 1 during 1999–2006) with a pronounced interannual variability of flow. The water budget shows a net dominance of through flow in the tidal mixing zone, while local precipitation and evapotranspiration play only a secondary role, at least in the wet season. During the dry season, the tidal flood reaches the upstream boundary of the study area during approximately 80 days per year on average. The groundwater field measurements indicate a mostly upwards-oriented leakage, which possibly equals the evapotranspiration term. The model results suggest a high importance of groundwater contribution to the water salinity in the EMER. The model performance is satisfactory during the dry season where surface flow in the area is confined to the Taylor River channel. The model also provided guidance on the importance of capturing the overland flow component, which enters the area as sheet flow during the rainy season. Overall, the modeling approach is suitable to reach better understanding of the water budget in the mangrove region. However, more detailed field data is needed to ascertain model predictions by further calibrating overland flow parameters.

Determination of deployment specific chemical uptake rates for SDB-RPD Empore disk using a passive flow monitor (PFM)

The use of the adsorbent styrenedivinylbenzene-reverse phase sulfonated (SDB-RPD) Empore disk in a chemcatcher type passive sampler is routinely applied in Australia when monitoring herbicides in aquatic environments. One key challenge in the use of passive samplers is mitigating the potentially confounding effects of varying flow conditions on chemical uptake by the passive sampler. Performance reference compounds (PRCs) may be applied to correct sampling rates ( R s ) for site specific changed in flow and temperature however evidence suggests the use of PRCs is unreliable when applied to adsorbent passive samplers. The use of the passive flow monitor (PFM) has been introduced for the assessment of site-specific changes in water flow. In the presented study we have demonstrated that the R s at which both atrazine and prometryn are accumulated within the SDB-RPD-Empore disk is dependent on the flow conditions. Further, the calibration of the measured R s for chemical uptake by the SDB-RPD-Empore disk to the mass lost from the PFM has shown that the PFM provides an accurate measure of R s for flow velocities from 0 to 16 cm s −1. Notably, for flow rates >16 cm s −1, a non linear increase in the R s of both herbicides was observed which indicates that the key resistance to uptake into the SDB-RPD Empore disk is associated with the diffusion through the overlying diffusion limiting membrane. Overall the greatest uncertainty remains at very low flow conditions, which are unlikely to often occur in surface waters. Validation of the PFM use has also been undertaken in a limited field study.

Occurrence and behaviour of nonylphenol and octylphenol in Nanming River, Guiyang City, China

Occurrence, variation and behaviour of nonylphenol (NP) and octylphenol (OP) were studied in surface water and groundwater in Guiyang, Guizhou Province, southwestern China. Discharge of wastewater from Guiyang City was the main source of alkylphenols (APs) entering the aquatic environment. The concentrations of NP and OP in river water ranged from 40 to 1582 ng L(-1) and from below the lowest limit of detection (LOD) to 67 ng L(-1), respectively. NP and OP were also detected in groundwater. Both NP and OP exhibited spatial and temporal variations in river water and groundwater. It was found that concentrations of NP and OP in river water was low upstream and dramatically increased downstream, and higher concentration of NP was found in winter compared to that in summer. Proportions of NP and OP were trapped by suspended particulate matter (SPM), which accounted for 7.6-50.0% and 3.4-25.6% of their total concentration in the river water system, respectively. Seasonal changes in water flow were responsible for the temporal variations of APs. To determine the behaviour of APs along the river, a mass balance equation based on chloride was used. The results showed that a mixing process was the predominant factor to determine upstream APs concentrations; while the discharge of wastewater controlled the concentrations of APs downstream. Considering the adverse effect of APs on organisms, combined effect modeling was used to assess the toxicity to fish. It was found that the predicted mixture effect for APs in river water on fish vitellogenin induction was low upstream and medium downstream, respectively.

Sustainability

This review on Sustainability covers selected journal articles and conferences papers published in 2010 and is divided into the following sections • Sustainable water and wastewater utilities: • Sustainable water resources management • Industrial and corporate approaches towards sustainability • Stormwater and green infrastructure • Sustainability in wastewater treatment • Life cycle assessment (LCA) applications • Sustainability and energy in wastewater industry • Sustainability and climate change • Sustainability and water reuse • Sustainability rating systems The sustainable water and wastewater utilities reviewed sustainable practices and sustainable workforce management. The stormwater and green infrastructure (GI) described the current development in five categories: new studies of GI and low impact development (LID) system performance; GI/LID system planning assessments; macro‐scale hydrologic and hydraulic modeling of GI/LID systems; efforts to model changes of water flow and quality in individual GI/LID systems; and social implications of GI/LID systems. The sustainability in wastewater treatment reviewed wastewater treatment; source separation; anaerobic technologies; wetland and low impact treatment systems; algae technologies; and the microbial fuel cell technology.

Ecology, changes in fisheries, and energy estimates in the middle stretch of the River Ganges

The River Ganges is the most important of all Indian rivers. It is being harnessed for several onsite and offsite benefits for various sections of society. Through varied man-induced interventions, over the years, the river system has recorded changes in its ecological functions, especially at some stations of the middle stretch viz., Kanpur, Varanasi and Allahabad. An attempt has been made in the present paper to understand changes with regard to key parameters of water quality, fish species composition and catches in this stretch, covering the highly populated major states of Uttar Pradesh and Bihar. For this purpose, data available over the years and some new data were utilized. These data reveal that siltation over the years has lowered water volumes and depths at various sections in the middle stretch with over 90% of the sediment comprising sand. The water quality in terms of pH remained higher (7.0 to 8.8) at some stations while dissolved oxygen remained lower (4.5 to 5.8 ppm) in comparison to upper and lower river stretches, suggesting progressive eutrophication. Other parameters, especially nutrients, also showed variations, coupled with variability in plankton density and primary productivity in this stretch reflecting changes in ecological functions. These changes coupled with various engineering interventions has resulted in drastic changes in water flows in the main river channel, the cumulative impact is evident in the drop in fish catches from 932 kg km−1 in the 1960s to 382 kg km−1 in the recent past, and the shift in species dominance from Indian major carps to less economic varieties. This has affected the livelihoods of fishers. The general lack of concern and awareness among the river authorities on requirements of river fishery management has been observed to be main reasons for these changes. Possible policy and governance interventions required to restore the river for sustainable fishery have also been suggested in this paper.

The impact of glide phases on the trackability of hydrodynamic trails in harbour seals (Phoca vitulina)

The mystacial vibrissae of harbour seals (Phoca vitulina) constitute a highly sensitive hydrodynamic receptor system enabling the seals to detect and follow hydrodynamic trails. In the wild, hydrodynamic trails, as generated by swimming fish, consist of cyclic burst-and-glide phases, associated with various differences in the physical parameters of the trail. Here, we investigated the impact of glide phases on the trackability of differently aged hydrodynamic trails in a harbour seal. As fish are not easily trained to swim certain paths with predetermined burst-and-glide phases, the respective hydrodynamic trails were generated using a remote-controlled miniature submarine. Gliding phases in hydrodynamic trails had a negative impact on the trackability when trails were 15 s old. The seal lost the generated trails more often within the transition zones, when the submarine switched from a burst to a glide moving pattern. Hydrodynamic parameter analysis (particle image velocimetry) revealed that the smaller dimensions and faster decay of hydrodynamic trails generated by the gliding submarine are responsible for the impaired success of the seal tracking the gliding phase. Furthermore, the change of gross water flow generated by the submarine from a rearwards-directed stream in the burst phase to a water flow passively dragged behind the submarine during gliding might influence the ability of the seal to follow the trail as this might cause a weaker deflection of the vibrissae. The possible ecological implications of intermittent swimming behaviour in fish for piscivorous predators are discussed.

Numerical study on the interaction among a nonlinear wave, composite breakwater and sandy seabed

Most previous investigations related to composite breakwaters have focused on the wave forces acting on the structure itself from a hydrodynamic aspect. The foundational aspects of a composite breakwater under wave-induced cyclic loading are also important in studying the stability of a composite breakwater. In this study, numerical simulations were performed to investigate the wave-induced pore water pressure and flow changes inside the rubble mound of the composite breakwater and seabed foundation. The validity and applicability of the numerical model were demonstrated by comparing numerical results with existing experimental data. Moreover, the present model clearly has shown that the instantaneous directions of pore water flow motion inside the seabed induced by surface waves are in good agreement with the general wave-induced pore water flow inside the seabed. The model is further used to discuss the stability of a composite breakwater, i.e., the interaction among nonlinear waves, composite breakwater and seabed. Numerical results suggest that the stability of a composite breakwater is affected by not only downward shear flow generating on the seaward slope face of the rubble mound but, also, a high and dense pore water pressure gradient inside the rubble mound and seabed foundation.

Beneath a floating ice shelf

Pine Island Glacier on West Antarctica's Amundsen Sea coast has experienced accelerating retreat over the past few decades. Oceanographic observations under the associated ice shelf show how changes in water flow and ice-cavity geometry have contributed to ice melting.