Backward location and travel time probabilities can be used to determine the prior of contamination in an aquifer. For a contaminant particle that was detected aquifer, backward probability is where located at some time. when position upgradient detection. These improve characterization known sources groundwater contamination, identify previously unknown sources, delineate capture zones. simple model domains, obtained heuristically from forward transport. multidimensional problems complex...

Backward location and travel time probabilities can be used to determine the former of contamination in an aquifer. For a contaminant parcel that was detected aquifer backward probability describes its position at some prior sampling, amount required for it sampling from upgradient position. These probabilities, which provide information about source contamination, are related adjoint states resident concentration. The governing equations adjoints forward equation, e.g., advection‐dispersion...

This paper proposes a new approach to the hydraulics of in situ groundwater remediation. In remediation promotes reactions between an injected treatment solution and contaminated groundwater, but without hydraulic mechanism promote spreading, laminar flows characteristic porous media will keep two fluids approximately same relative configuration as they travel through aquifer, limiting opportunity for occur. To address this fundamental limitation, borrows key result from fluid mechanics...

The forward Fractional Advection Dispersion Equation (FADE) provides a useful model for non-Fickian transport in heterogeneous porous media. space FADE captures the long leading tail, skewness, and fast spreading typically seen concentration profiles from field data. This paper develops corresponding backward model, to identify source location release time. method is developed theory of inverse problems, then explained stochastic point view. resultant differs significantly traditional (ADE)...

Inverse methods can be used to reconstruct the release history of a known source groundwater contamination from concentration data describing present‐day spatial distribution contaminant plume. Using hypothetical functions and plumes, we evaluate relative effectiveness two proposed inverse methods, Tikhonov regularization (TR) minimum entropy (MRE) inversion, in reconstructing conservative one‐dimensional domain [ Skaggs Kabala , 1994; Woodbury Ulrych 1996]. We also address issues...

[1] During in situ remediation, a treatment solution is often injected into contaminated aquifer to degrade the groundwater contaminant. Since contaminant degradation reactions occur only at locations where and overlap, mixing of necessary for reaction occur. Mixing results from molecular diffusion pore-scale dispersion, which operate over small length scales; thus, during remediation can separation distance between small. To promote mixing, advection be used spread increase extent region...

During in situ remediation of contaminated groundwater, a treatment solution is often injected into the region to initiate reactions that degrade contaminant. Degradation only occur where and groundwater are close enough mixing will bring them together. enhanced when spread region, thereby increasing spatial extent degradation reactions. Spreading results from local velocity variations emerge aquifer heterogeneity external forcings drive flow. Certain patterns have been shown create chaotic...

Abstract Engineered injection and extraction (EIE) is an in situ groundwater remediation strategy that imposes engineered spatially temporally varying velocity field to spread amendment into the contaminant plume promote mixing degradation through reaction. Here we present a coordinated suite of laboratory experiments numerical simulations apply EIE using two pumping sequences: A folding sequence manipulates geometry by stretching folding, oscillating perpendicular interface accordance with...

Backward location and travel time probability density functions characterize the possible former locations (or source location) of contamination that is observed in an aquifer. For contaminant particle backward function (PDF) describes its position at a fixed prior to sampling, amount required for sampling from upgradient position. The model has been developed single observation (e.g., Neupauer Wilson, 1999). In practical situations, sampled multiple times, these additional data provide...

Flooding affects ecosystems by transporting water and solutes across aquatic‐terrestrial interfaces, removing nutrient organic substrate limitations, spurring biogeochemical activity. Few studies have considered the influence of flooding on surface water–groundwater interactions. This research examines temporally variable storage exchange in a stream McMurdo Dry Valleys (MDV) Antarctica, where diel flood pulses occur due to glacial melt. Several MDV streams display truncated discharge peaks,...

Stream depletion, which is the reduction in flow rate of a stream or river due to extraction groundwater hydraulically connected stream-aquifer system, often estimated using numerical models. The accuracy these models depends on appropriate parameterization aquifer and streambed hydraulic properties. Streambed conductance parameter that relates head difference between across channel. It function conductivity geometry. In natural systems, varies spatially throughout streambed; however,...

Abstract Fractures in frozen soils (frost quakes) can cause damage to buildings and other infrastructure, but their formation mechanisms remain poorly understood. A methodology was developed assess thermal stress on soil due changes climate weather conditions investigate the connection between frost quakes central Finland brittle fracturing uppermost soils. hydrological model used simulate snow accumulation melt, a temperature at different depths beneath pack. The results of modeling,...

Abstract Spatiotemporal fractional‐derivative models (FDMs) have been increasingly used to simulate non‐Fickian diffusion, but methods not available define boundary conditions for FDMs in bounded domains. This study defines and then develops a Lagrangian solver approximate bounded, one‐dimensional fractional diffusion. Both the zero‐value nonzero‐value Dirichlet, Neumann, mixed Robin are defined, where sign of Riemann‐Liouville derivative (capturing spatial‐nonlocal with directional...

Abstract Backward location and travel time probabilities can be used to characterize known unknown sources or prior positions of ground water contamination. probability describes the position observed contamination at some in past; backward amount observation that was released from its source a particular upgradient location. The governing equation for is adjoint contaminant transport, but with new load terms. Numerical codes have been written solve forward equations e.g.,...

If contamination is observed in an aquifer, a backward probability model can be used to obtain information about the former position, source location, or release time of contamination. A location density function (PDF) describes possible positions contaminant particle at specified past and identify source. travel times from known upgradient observation determine Neupauer Wilson (1999, 2001, 2002) obtained PDFs that depend on locations sampling times, addition transport properties aquifer...

Pollutant source identification (PSI) has been conducted for four decades tracking Fickian diffusive pollutants, while PSI non-Fickian diffusion, well-documented in aquifers and rivers, requires novel, predictive models. To enable this study derived a general backward model using the fractional-adjoint approach sensitivity analysis dissolved contaminants with transport governed by spatiotemporal fractional advection–dispersion equation (fADE). The fADE contains self-adjoint time-fractional...

Wavelet analysis is an image technique that can extract local information at multiple scales. Because of this capability, wavelet be used to identify dominant scales in statistically heterogeneous and anisotropic random fields. We develop test a method for identifying orientations permeability fields boundaries between regions with different orientations. evaluate three wavelets (fully Morlet wavelet, Mexican hat Cauchy wavelet) show the most effective these also investigate use several...

If a contamination event occurs in water distribution system, sensors the network may observe quality changes. The data from these can be used to identify source of contamination. binary that record presence or absence contamination, fuzzy measure concentration within set range, perfect exact bounds measurement uncertainty. This work presents an adjoint-based probabilistic approach for identifying node, release time, and strength instantaneous based on sensor observations known system...

If a chemical or biological agent is released into water distribution system, sensors that are installed in the pipe network may detect contamination as it travels through system. To minimize adverse impact of contaminant release, source must be characterized to determine extent and remediate contaminated area. We present backward modeling approach uses data collected by obtain probability density functions describe random time past observed was at particular upgradient position. These can...