Hydraulic Signatures Research Articles

Adjoint-based sensitivity analysis and assimilation of multi-source data for the inference of spatio-temporal parameters in a 2D urban flood hydraulic model

This contribution presents a novel approach for the calibration of distributed parameters in a 2D urban flood hydraulic model. It focuses on the challenging issue of inferring distributed friction parameters from multi-source heterogeneous spatio-temporal observations of their hydraulic signatures in the context of an urban flash flood in a complex street network. A variational data assimilation algorithm is used to infer high-dimensional multi-variate parameters (spatialized friction and inflow discharge time series) using multi-source observations. This method relies on a differentiable 2D shallow water hydraulic model which enables to generate high-resolution sensitivity maps of local gradients and Derivative-based Global Sensitivity Measures (DGSM), enabling to guide adequate definition of parameter spatialization for the data assimilation process. Assimilated data include real local limnigraphic measurements and high-water marks collected after a major flood event, as well as modeled flow velocity used in twin experiments setups. This study is the first to leverage high-water marks with a variational method for the calibration of distributed parameters in an urban flood model. The multi-source data is used to infer inflow hydrographs and distributed friction parameters in setups of varying complexity. In the main setup, the complex structure of the street network, along with the sensitivity maps and hydraulics expertise led to define a model configuration with 45 friction patches. A high-dimensional parameter vector composed of these friction values and an upstream inflow is inferred simultaneously by assimilating real limnigraphic data and high-water marks. This leads to an increase in model fit to observations and satisfying parameter estimates.

The influence of large wood on sediment routing and flow characteristics: A study in a low-order stream in the southern brazilian plateau

The coupling of sediment sources varies in terms of efficiency and availability based on the frequency and intensity patterns of rainfall events over time. It is commonly assumed that reaches with steeper gradients have higher longitudinal connectivity, while lower gradient reaches have lower longitudinal connectivity. However, considering that the longitudinal connectivity of channels is not always perfectly established, this conception regarding channel gradient may not always hold true. In forested regions, elements such as large wood can be the main agents of this disconnectivity. Thus, this study investigates the effects of large wood on sediment flux, flow characteristics and channel morphology in the context of the Atlantic Forest Biome in a low-order stream in the southern Brazilian plateau. To achieve this, measurements of hydrological variables, characterization of sediments, and channel morphology were conducted. Hydraulic and morphological variables were estimated to define hydraulic signatures for each river section. The influences of large wood barriers in the study section were highlighted through an analysis of hydraulic characteristics at different cross-sections and the assessment of morphological variables. The investigation revealed a tendency for a reduction in velocity of approximately 90 % in low-discharge conditions in sections where large wood barriers were present. In the case of high-magnitude events, the velocity reduction was considerably lower. Additionally, it was found that each large wood deposit presented uniqueness, and the structural characteristics of each reflected the potential for system disconnectivity. Finally, it was observed that both barriers have the capacity to store sediments, leading to the constriction of the cross-section due to the formation of sediment bars, although surveys revealed that fine sediments were poorly retained in both barriers.

A comprehensive analysis of thermal–hydraulic signatures in neutron noise of WWER-type reactors

The neutron noise phenomenon, occurring in all types of nuclear reactors, provides valuable insights into the dynamic behavior of these reactors. In this work, a well-justified approach for modeling neutron noise induced by thermal–hydraulic sources in a hexagonal reactor core is presented in detail. These sources encompass fluctuations in key features of the inlet coolant, including flow rate, temperature, and boric acid concentration. Our proposed approach touches on various aspects of the distribution of thermal–hydraulic parameters among coolant loops, accounting for both uniform and non-uniform distributions. The latter allows for the asymmetric and asynchronous distribution of their fluctuating component among the coolant loops. To manage such complexity, it becomes imperative to determine the contribution of each fuel assembly based on each coolant loop. To achieve this, CFD simulations are conducted for the downcomer and lower plenum of the reactor pressure vessel. These simulations provide essential data to establish the coolant mixing matrix, which accounts for non-uniform distributions. The obtained mixing matrix is subsequently integrated into our neutron noise simulator, DYNOSIM, ensuring the faithful reproduction of neutron noise. Our study comprehensively analyzes both uniform and non-uniform scenarios. The radial and axial distributions of neutron noise amplitude and phase are examined for these scenarios. Their qualitative verifications are conducted by prior works in this field. Furthermore, we compare one of the uniform scenarios with reference results obtained using a frequency domain simulator. Notably, our CFD simulation results closely match the experimental data. Our findings demonstrate the effectiveness and efficiency of this methodology in modeling and understanding neutron noise in hexagonal reactor cores.

Ocean acidification modifies behaviour of shelf seabed macrofauna: A laboratory study on two ecosystem engineers, Abra alba and Lanice conchilega

The feeding activity and burrow ventilation by benthic invertebrates importantly affect the biodiversity and functioning of seafloor sediments. Here we investigated how ocean acidification can modify these behavioural activities in two common and abundant macrofaunal ecosystem engineering species in temperate continental shelf communities: the white furrow shell Abra alba and the sand mason Lanice conchilega. Using time-lapse imagery and sediment porewater hydraulic signatures we show that both species adapt their behaviour in response to predicted future pH conditions (−0.3 units). During a three-week laboratory experiment, A. alba reduced the duration per feeding event when suspension and deposit feeding (by 86 and 53%, respectively), and almost completely ceased suspension feeding under reduced seawater pH in comparison to ambient seawater pH (pH ∼ 8.2). This behavioural change reduces the intake of low pH water during feeding and respiration. L. conchilega increased its piston-pumping frequency by 30 and 52%, respectively, after one and two weeks of exposure to future pH conditions (−0.3 units) relative to ambient conditions. This change in irrigation activity suggests higher metabolic demands under low seawater pH, and also extended low water column pH conditions deeper into the seafloor. Because the distribution of other populations depends on the physicochemical setting by our focal species, we argue that the demonstrated behavioural plasticity will likely have cascading effects on seafloor diversity and functioning, highlighting the complexity of how ocean acidification, and climate change in general, will affect seafloor ecology.

Using multi-event hydrologic and hydraulic signatures from water level sensors to diagnose locations of uncertainty in integrated urban drainage models used in living digital twins.

Digital twins of urban drainage systems require simulation models that can adequately replicate the physical system. All models have their limitations, and it is important to investigate when and where simulation results are acceptable and to communicate the level of performance transparently to end users. This paper first defines a classification of four possible 'locations of uncertainty' in integrated urban drainage models. It then develops a structured framework for identifying and diagnosing various types of errors. This framework compares model outputs with in-sewer water level observations based on hydrologic and hydraulic signatures. The approach is applied on a real case study in Odense, Denmark, with examples from three different system sites: a typical manhole, a small flushing chamber, and an internal overflow structure. This allows diagnosing different model errors ranging from issues in the underlying asset database and missing hydrologic processes to limitations in the model software implementation. Structured use of signatures is promising for continuous, iterative improvements of integrated urban drainage models. It also provides a transparent way to communicate the level of model adequacy to end users.

Generation and analysis of stage-fall-discharge laws from coupled hydrological-hydraulic river network model integrating sparse multi-satellite data

Current and forthcoming altimetry satellites provide increasing hydraulic visibility of river surface variabilities. However, due to unobservable river bathymetry and friction, as well as the sampling and quality of remote sensing data, discharge estimation remains a challenging problem. This paper proposes a new rigorous methodology to estimate stage-fall-discharge laws at any point of a hydrographic network including backwater affected reaches. This methodology is adapted to operational estimation of discharge from multi-mission satellite altimetry data. The cornerstone of the method is to take advantage of meaningful hydraulic signatures, including water surface slopes, simulated by a river network model optimally combined with multi-satellite noisy observations. This optimal combination of heterogeneous multi-source data with a river network model is achieved through variational data assimilation performed using the DassFlow-HiVDI hydraulic model inflowed by MGB regional hydrological model. It is newly applied to the large and complex Negro-Branco River network in the Amazon basin. An effective model is obtained by variational calibration using Jason-3 and Sentinel-3A and -3B altimetry observations between February 2016 and May 2019. A fairly good fit bellow 1m for 80% of the altimetric observations is obtained. Using this hydrodynamic model as a fine spatio-temporal extrapolator of hydraulic quantities, and in particular of multi-scale water surface slope signatures, the parameters of a general SFD law, as well as the uncertainties estimations, can be constrained at any location within the river network domain using a Bayesian optimization method. This methodology is tested over 4 virtual stations representing various hydraulic complexities. Accurate discharge estimates and meaningful SFD parameters are obtained compared to those of the reference low Froude model at these locations. Analyses are also performed on a reference case with fine-scale bathymetry data of the Garonne River, France. The strength of the method lies in its applicability to noisy multi-satellite data while ensuring physical consistency. It should be applicable in real time to any river basin, using nadir altimetry only or combined to the forthcoming SWOT satellite data. Moreover, the method allows to take full advantage, via the hydrodynamic model, of variable water masks observations and physical segmentations of river networks. The method is implemented in the open source hydrodynamic data assimilation platform DassFlow.

Estimation of multiple inflows and effective channel by assimilation of multi-satellite hydraulic signatures: The ungauged anabranching Negro river

With the upcoming SWOT satellite mission, which should provide spatially dense river surface elevation, width and slope observations globally, comes the opportunity to assimilate such data into hydrodynamic models, from the reach scale to the hydrographic network scale. Based on the HiVDI (Hierarchical Variational Discharge Inversion) modeling strategy (Larnier et al. (2020)), this study tackles the forward and inverse modeling capabilities of distributed channel parameters and multiple inflows (in the 1D Saint–Venant model) from multisatellite observations of river surface. It is shown on synthetic cases that the estimation of both inflows and distributed channel parameters (bathymetry-friction) is achievable with a minimum spatial observability between inflows as long as their hydraulic signature is sampled. Next, a real case is studied: 871km of the Negro river (Amazon basin) including complex multichannel reaches, 21 tributaries and backwater controls from major confluences. An effective modeling approach is proposed using (i) WS elevations from ENVISAT data and dense in situ GPS flow lines (Moreira (2016)), (ii) average river top widths from optical imagery (Pekel et al. (2016)), (iii) upstream and lateral flows from the MGB large-scale hydrological model (Paiva et al. (2013a)). The calibrated effective hydraulic model closely fits satellite altimetry observations and presents real-like spatial variabilities; flood wave propagation and water surface observation frequential features are analyzed with identifiability maps following (Brisset et al. (2018)). Synthetic SWOT observations are generated from the simulated flowlines and allow to infer model parameters (436 effective bathymetry points, 17 friction patches and 22 upstream and lateral hydrographs) given hydraulically coherent prior parameter values. Inferences of channel parameters carried out on this fine hydraulic model applied at a large scale give satisfying results using noisy SWOT-like data at reach scale. Inferences of spatially distributed temporal parameters (lateral inflows) give satisfying results as well, with even relatively small scale hydrograph variations being inferred accurately on this long reach. This study brings insights in: (i) the hydraulic visibility of the signatures of multiple inflow hydrographs at a large scale with SWOT; (ii) the simultaneous identifiability of spatially distributed channel parameters and inflows by assimilation of satellite altimetry data; (iii) the need for prior information; (iv) the need to further tailor and scale network hydrodynamic models and assimilation methods to improve the fusion of multisource information and potential information feedback to hydrological modules in integrated chains.

Pattern Recognition and Clustering of Transient Pressure Signals for Burst Location

A large volume of the water produced for public supply is lost in the systems between sources and consumers. An important—in many cases the greatest—fraction of these losses are physical losses, mainly related to leaks and bursts in pipes and in consumer connections. Fast detection and location of bursts plays an important role in the design of operation strategies for water loss control, since this helps reduce the volume lost from the instant the event occurs until its effective repair (run time). The transient pressure signals caused by bursts contain important information about their location and magnitude, and stamp on any of these events a specific "hydraulic signature". The present work proposes and evaluates three methods to disaggregate transient signals, which are used afterwards to train artificial neural networks (ANNs) to identify burst locations and calculate the leaked flow. In addition, a clustering process is also used to group similar signals, and then train specific ANNs for each group, thus improving both the computational efficiency and the location accuracy. The proposed methods are applied to two real distribution networks, and the results show good accuracy in burst location and characterization.

Experimental characterization of various scale hydraulic signatures in a flooded branched street network

ABSTRACTUnderstanding urban flood flow repartition mechanisms within street network remains challenging. This paper presents an experimental dataset of water depth and velocity profiles in the Icube experimental rig. The spatial variability of discharge along a street is highlighted. Comparing the water depth gradient orientation and the flow repartition promotes for complex repartition mechanisms at small scales. Comparable unit-discharge values are observed in both large and narrow streets. Interestingly, the intensity of the discharge deviation at the crossroad scale is related with the asymmetry of the velocity profile entering a crossroad. Moreover, discharges at the crossroad and the subdistrict scales show that downscaling of the flow repartition relationship is difficult. At real scale, results show that inflow velocity profile asymmetry may persist on a distance of several street widths downstream of a crossroad. Such distances are insufficient to consider disconnected crossroads as done in the literature to establish discharge repartition relationships.

Insights on pumping well interpretation from flow dimension analysis: The learnings of a multi-context field database

The flow dimension parameter n, derived from the Generalized Radial Flow model, is a valuable tool to investigate the actual flow regimes that really occur during a pumping test rather than suppose them to be radial, as postulated by the Theis-derived models. A numerical approach has shown that, when the flow dimension is not radial, using the derivative analysis rather than the conventional Theis and Cooper-Jacob methods helps to estimate much more accurately the hydraulic conductivity of the aquifer. Although n has been analysed in numerous studies including field-based studies, there is a striking lack of knowledge about its occurrence in nature and how it may be related to the hydrogeological setting. This study provides an overview of the occurrence of n in natural aquifers located in various geological contexts including crystalline rock, carbonate rock and granular aquifers. A comprehensive database is compiled from governmental and industrial sources, based on 69 constant-rate pumping tests. By means of a sequential analysis approach, we systematically performed a flow dimension analysis in which straight segments on drawdown-log derivative time series are interpreted as successive, specific and independent flow regimes. To reduce the uncertainties inherent in the identification of n sequences, we used the proprietary SIREN code to execute a dual simultaneous fit on both the drawdown and the drawdown-log derivative signals. Using the stated database, we investigate the frequency with which the radial and non-radial flow regimes occur in fractured rock and granular aquifers, and also provide outcomes that indicate the lack of applicability of Theis-derived models in representing nature. The results also emphasize the complexity of hydraulic signatures observed in nature by pointing out n sequential signals and non-integer n values that are frequently observed in the database.

Assessing instream habitat suitability and hydraulic signatures of geomorphic units in a reconstructed single thread meandering channel

AbstractStream channel reaches consist of a series of geomorphic units (e.g. pools, runs and riffles) that mitigate flow velocity and provide a variety of aquatic habitat. The hydraulic signature of each geomorphic unit is unique and should remain so during variable flow conditions in order to satisfy habitat requirements. We use the hydraulic signatures measured at different geomorphic units in a recent channel realignment project to evaluate suitability of reaches and geomorphological units for target fish species. In 2009, 650 m of creek and valley were realigned in Brampton, Ontario, to facilitate development. In 2013, water velocity, depth, temperature and channel substrate were measured at cross‐sections between 1 May and 15 October. The assessment illustrated that while geomorphic units have unique signatures during moderate to low‐flow conditions, at high‐flow conditions the boundaries between geomorphic units blurred. Furthermore, our findings suggest that suitable water depth, velocity and temperature conditions existed at least 68% of the time over the entire study period but was reduced during the estimated spawning period for the target species. Specifically, water depth was only ideal for approximately 38% of the spawning period. Finally, in cases where both geomorphic and ecologic systems interface (e.g. channel restoration), it is important to view the whole picture. This study contributes to the on‐going discussion on restoration and success and is particularly useful in light of recent stream restoration trends in rapidly expanding urban regions around the globe. Copyright © 2015 John Wiley & Sons, Ltd.

John Hancock is in the Sewers? How Understanding Hydraulic Signatures With Models Will Improve SSO Root Cause Analysis

John Hancock is in the Sewers? How Understanding Hydraulic Signatures With Models Will Improve SSO Root Cause Analysis

Physical Modeling of Particulate Matter Washout from a Hydrodynamic Separator

AbstractA hydrodynamic separator (HS) is commonly used as a preliminary unit operation for separation of coarser particulate matter (PM) and PM-associated constituents transported by urban rainfall-runoff. Although the small spatial footprint of an HS is advantageous for integration into sewer (storm or combined) or drainage systems, the small footprint also concentrates flow energy. In many HS units, where PM sludge is not isolated or in units that are not maintained (cleaned), washout of previously separated PM sludge can result in a net export of PM. This study analyzes PM washout from a baffled HS as a function of steady-flow rates and particle-size distributions (PSDs) guided by a physical modeling framework utilized for scour certification. The HS hydraulic signature is determined through velocity measurements and a residence time distribution (RTD) analysis. As a function of surface overflow rate (SOR), the predeposited PM washout rate ranges from 0.4 to 13.3 g/min for fine PM (sandy silt, SM <75 ...

Numerical modeling of the hydraulic signatures of horizontal and inclined faults

Pumping tests in discontinuous media are commonly interpreted using radial/non-radial flow analytical models, which do not account for a large range of multistage real signatures that combine both flow types. The term radial is employed in Barker’s sense, referring to the cross-flow area growth with a flow dimension (n) equal to 2, while multistage refers to a flow response of several time periods with successive n values. Synthetic domains are used to numerically investigate the flow behaviour of faulted media, specifically the effect of fault inclination on multistage signatures. Simulations are performed using single faults surrounded by a permeable matrix to characterize drawdown series and to identify hydrodynamic scenarios associated with some diagnostic multistage n sequences. The n sequence 2 – < 2 – 2 results from interactions between the matrix and a horizontal to weakly inclined fault, while 2 – 1.5 – 2 corresponds to a higher fault inclination and is a combination of the generalized horizontally and vertically faulted models. These results improve the interpretation of ambiguous drawdown series from long-term pumping tests. This provides a better hydraulic characterization of faulted environments, allowing assessment of fault and matrix properties such as fault inclination. The approach is successfully tested on real datasets.

Relationships between mesoscale morphological units, stream hydraulics and Chinook salmon ( Oncorhynchus tshawytscha) spawning habitat on the Lower Yuba River, California

An expert-based approach was used to identify 10 morphological unit types within a reach of the gravel bed, regulated Yuba River, California, that is heavily utilized by spawning Chinook salmon ( Oncorhynchus tshawytscha). Analysis of these units was carried out using two-dimensional hydrodynamic modeling, field-based geomorphic assessment, and detailed spawning surveying. Differently classified morphological units tended to exhibit discrete hydraulic signatures. In most cases, the Froude number adequately differentiated morphological units, but joint depth–velocity distributions proved the most effective hydraulic classification approach. Spawning activity was statistically differentiated at the mesoscale of the morphological unit. Salmon preferred lateral bar, riffle, and riffle entrance units. These units had moderately high velocity (unit median > 0.45 m s − 1 ) and low depth (unit median < 0.6 m), but each exhibited a unique joint depth–velocity distribution. A large proportion of redds (79%) were associated with conditions of convective flow acceleration at riffle and riffle entrance locations. In addition to reflecting microhabitat requirements of fish, it was proposed that the hydraulic segregation of preferred from avoided or tolerated morphological units was linked to the mutual association of specific hydraulic conditions with suitable caliber sediment that promotes the provision and maintenance of spawning habitat.

Hydraulic signatures for ecological modelling at different scales

The quantitative description of the aquatic space is essential for ecohydraulic modelling. It is recommended to quantify the hydraulic variety for a given flow and any area of the aquatic space by calculating the volume or surface percentages in a depth and current velocity cross-classification. This representation in the velocity–depth plane is called a hydraulic signature. ‘HydroSignature’ is a free beta software used to calculate signatures and can be downloaded at: http://hydrosignature.aix.cemagref.fr/

Overprinting faulting mechanisms in high porosity sandstones of SE Utah

Normal faults in sandstone of the Jurassic Entrada Formation, South-East Utah formed by two mechanisms: (1) deformation band faulting overprinted by (2) jointing and subsequent shearing along joints. Fundamental structural elements of deformation band faults are single deformation bands, zones of deformation bands, and slip surfaces. Joint-based faults are composed of joints, sheared joints, splay fractures, fragmentation zones, breccia, and fine-grained fault rock. We demonstrate that both mechanisms contribute to slip in a single fault zone with joint-based faulting consistently postdating deformation band faulting at a given location along a fault. The occurrence, distribution, and geometric arrangement of structures formed by the two mechanisms resulted in faults with distinct fault architecture. This fault architecture is related to the relative contributions of each deformation mechanism to the total offset and to their relative timing. Overprinting of a deformation band-based fault by a joint-based mechanism introduces extensive localized structural heterogeneity with a distinct hydraulic signature. Whereas deformation bands tend to act as fluid baffles, joints may act as preferred fluid conduits. Therefore, fluid flow properties such as the permeability of the faults with overlapping mechanisms are expected to change over time accompanying the overprinting process.

Permanent water level drop associated with the Spitak Earthquake: observations at Lisi Borehole (Republic of Georgia) and modelling

We present the results of a series of measurements that were made between 1988 and 1992 at Lisi (Georgia). Water level variations in the Lisi well, barometric pressure, precipitation (including rain and snow) and temperature measurements were made during this period. A hydraulic ‘slug test’ has been performed more recently in the well. Two major seismic events occurred during the observation period in the Caucasus area. The Spitak seismic event of 1988 December 9, 110 km from the Lisi borehole, left a clear post-seismic hydraulic signature, whereas the second event, that of 1991 April 29, 125 km from the borehole, did not seem to induce any detectable anomaly. First, we analyse the tidal and barometric responses of the water level in order to calibrate the borehole and to determine the hydraulic parameters of the aquifer. Then we develop a model for aquifer recharge by meteoric precipitation. Finally, we compare our model with the observed water level variations in the well. We highlight anomalous behaviour that correlates with the earthquake, with the following characteristics: the water level drops about 75 cm with a time constant of 6.6 days. The initial water level is never recovered and the change appears permanent on the scale of the period of observation. Since it is delayed in time, the anomalous water level cannot be attributed to coseismic deformation. Following the suggestion of some authors that the observed behaviour could be related to damage of the aquifer due to the passage of seismic waves, we attempted to take this process into account and to model the resulting water level variations in the aquifer. A double porosity model (including fractures and a porous medium) has been used to describe the modifications undergone by the medium. The medium is discretized at two different scales—(1) at the scale of a porous block and (2) at the scale of the fractured system (which may include a finite number of porous blocks). Using this basic model we have tested three interpretative models: (1) a variable-permeability model; (2) a locally varying porosity model; (3) a model combining (1) and (2). We show that an increase in permeability by a factor of 2 is needed in order to describe the permanent water level drop, whilst the locally varying porosity zones account for the observed time constants of the anomaly. Using this model, simulations show that we are able to describe water level variation associated with precipitation for the whole period of observation.

A Probabilistic Method for Estimating Monitoring Point Density for Containment System Leak Detection

AbstractThe use of physical and hydraulic containment systems for the isolation of contaminated ground water and aquifer materials associated with hazardous waste sites has increased during the last decade. The existing methodologies for monitoring and evaluating leakage from hazardous waste containment systems rely primarily on limited hydraulic head data. The number of hydraulic head monitoring points available at most sites employing physical containment systems may be insufficient to identify significant leaks from the systems. A probabilistic approach for evaluating the performance of containment systems, based on estimations of apparent leakage rates, is used to introduce a methodology for determining the minimum number of monitoring points necessary to identify the hydraulic signature of leakage from a containment system. The probabilistic method is based on the principles of geometric probability. The method is demonstrated using three‐dimensional ground water flow modeling results of leakage through a vertical barrier. The results indicate that the monitoring point spacing used at many hazardous waste sites likely is inadequate to detect the hydraulic signatures of all but the largest leaks.