- Groundwater flow and contamination studies
- Hydraulic Fracturing and Reservoir Analysis
- Soil and Unsaturated Flow
- Reservoir Engineering and Simulation Methods
- Geophysical and Geoelectrical Methods
- Soil Geostatistics and Mapping
- Hydrology and Watershed Management Studies
- Dam Engineering and Safety
- Groundwater and Isotope Geochemistry
- Landslides and related hazards
- Complex Systems and Time Series Analysis
- Advanced Mathematical Modeling in Engineering
- Geochemistry and Geologic Mapping
- Hydrology and Drought Analysis
- Seismic Imaging and Inversion Techniques
- Water resources management and optimization
- Hydrological Forecasting Using AI
- Advanced Numerical Methods in Computational Mathematics
- Probabilistic and Robust Engineering Design
- Financial Risk and Volatility Modeling
- Water Systems and Optimization
- Numerical methods in inverse problems
- Enhanced Oil Recovery Techniques
- Drilling and Well Engineering
- Geotechnical and Geomechanical Engineering
University of Arizona
2010-2020
Los Alamos National Laboratory
2001
Hebrew University of Jerusalem
1987
Pacific Island Ecosystems Research Center
1985
United States Geological Survey
1985
University of California, Berkeley
1970-1977
Agricultural Research Organization
1971-1977
Lawrence Berkeley National Laboratory
1977
In this series of three papers a method is presented to estimate the parameters groundwater flow models under steady and nonsteady state conditions. The include values directions principal hydraulic conductivities (or transmissivities) in anisotropic media, specific storage storativity), interior boundary recharge or leakage rates, coefficients head‐dependent sources, heads. transient situations, initial head distribution can also be estimated if system originally at state. Paper 1 discusses...
An interpretation is offered for the observation that dispersivities increase with scale. Apparent longitudinal dispersivity data from a variety of hydrogeologic settings are assumed to represent continuous hierarchy log hydraulic conductivity fields mutually uncorrelated increments, each field having its own exponential autocovariance, associated integral scale, and variance increases as power Such shown theoretically form self‐similar random homogeneous increments. Regardless whether or...
Paper 2 of this three‐part series starts with a discussion the question, Under what conditions is aquifer inverse problem well‐posed? After defining terms uniqueness, identifiability, and stability, theoretical considerations synthetic examples are used to demonstrate that ill‐posedness can be mitigated by including prior information about parameters in estimation criterion minimized. At same time, inclusion such shown insufficient guarantee uniqueness stability all cases. Several test...
A new analytical model is proposed for the delayed response process characterizing flow to a well in an unconfined aquifer. The present approach differs from that of Boulton [1954 b , 1963, 1970] and Pontin [1971] it based only on well‐defined physical parameters aquifer system. Therefore provides possible explanation mechanism water table eliminates conceptual difficulties encountered with Boulton's theory ‘delayed yield storage above table.’ Contrary prevailing belief homogeneous...
A Galerkin-type finite element method is employed to solve the quasilinear partial differential equations of transient seepage in saturated-unsaturated porous media. The resulting computer program capable handling nonuniform flow regions having complex boundaries and arbitrary degrees local anisotropy. Flow can take place a vertical plane, horizontal or three-dimensional system with radial symmetry. An number faces be considered simultaneously, positions exit points on these are adjusted...
Previously a new analytical model was proposed by the author for delayed response process characterizing flow to well in an unconfined aquifer. The approach differs from that of Boulton (1954, 1963, 1970, 1973) and Pontin (1971) it is based only on well‐defined physical parameters aquifer system. As such, can be used develop methods determining hydraulic properties anisotropic aquifers field drawdown data. Two analysis are described, one matching data with theoretical type curves other...
Previously, a new analytical model was proposed by the author for delayed response process characterizing flow to well in an unconfined aquifer. It shown that contrary prevailing belief this can be simulated using constant values of specific storage and yield without recourse unsaturated theory. In present work theory is extended account effect partially penetrating homogeneous anisotropic Field laboratory evidence quoted suggest elastic properties aquifers may often much more pronounced...
Data obtained from careful water balance studies on uptake by the roots of red cabbage are compared with results a modified numerical model Nimah and Hanks. In air dry moisture content at soil surface may vary time depending meteorological conditions. The maximum possible rate evapotranspiration is calculated considering both conditions crop properties. quoted to suggest that coefficient root sink sometimes exponentially depth. A period 7 weeks was simulated, weekly profiles did not agree...
A three‐dimensional theory is described for field‐scale Fickian dispersion in anisotropic porous media due to the spatial variability of hydraulic conductivities. The study relies partly on earlier work by authors attributes which are briefly reviewed. It leads results differ important ways from theoretical conclusions about media. We express tensor D as sum a local component d and Δ. assumed be independent velocity (which most appropriate if it represents molecular diffusion) its principal...
A complete analytic solution has been developed for the problem of flow to a well in confined infinite radial system composed two aquifers that are separated by an aquitard. The well, which is represented line sink, completely penetrates only one and discharges at constant rate. present differs from previous work effects storage aquitard drawdown unpumped aquifer both considered. Asymptotic solutions small values time also included. have evaluated numerically selected cases. validity these...
Owing to the deterministic nature of most groundwater flow models there has been a tendency in past overlook strong element uncertainty that invariably enters into problem parameter identification. It is shown because this an approach based on minimization single error functional does not general lead satisfactory results. A multiple‐objective decision process postulated taking account all available information aquifer system as well range environmental conditions under which expected...
The last paper of this three‐part series illustrates and explores various features the methodology we have proposed in papers 1 2 (J. Carrera S. P. Neuman, issue ( a, b )) by applying it to a synthetic test case set field data from southwestern United States. In addition demonstrating ability our method estimate model parameters under variety conditions, example is used investigate relative worth transient steady state terms their bring about an improvement quality estimates. A similar...
We consider the effect of measuring randomly varying local hydraulic conductivities K ( x ) on one's ability to predict steady state flow within a bounded domain, driven by random source and boundary functions. More precisely, we prediction head h Darcy flux q means their unbiased ensemble moments 〈 )〉 κ conditioned measurements ). These predictors satisfy deterministic equation in which = −κ( )∇〈 + r ), where κ( is relatively smooth estimate “residual flux.” derive compact integral...
The permeabilities and dispersivities of geologic media are known to vary with the scale observation. Particularly well documented is consistent increase in apparent longitudinal dispersivity mean travel distance a tracer. This has been previously interpreted by author imply that many scale, on average, according power‐law semivariogram γ (s)=c √ s where c constant distance. Tracer test data support this conclusion indirectly at least over scales from 10 cm 3,500 m. present paper cites...
Hydrologic systems are open and complex, rendering them prone to multiple conceptualizations mathematical descriptions. There has been a growing tendency postulate several alternative hydrologic models for site use model selection criteria (1) rank these models, (2) eliminate some of them, and/or (3) weigh average predictions statistics generated by models. This led debate among hydrogeologists about the merits demerits common (also known as discrimination or information) such AIC , AICc BIC...
A unified Eulerian‐Lagrangian theory is presented for the transport of a conservative solute in random velocity field that satisfies locally ∇ · v ( x , t) = f t), where function including sources and/or time derivative head. Solute concentration Eulerian equation ∂ c t)/∂ t + J g advective flux and source independent t). We consider prediction by means their unbiased ensemble moments 〈 t)〉 ν conditioned (as implied subscript) on local hydraulic measurements through use latter obtaining...
Geology is ubiquitously heterogeneous, exhibiting both discrete and continuous spatial variations on a multiplicity of scales. It therefore natural to expect that hydrogeologic other geophysical variables would do likewise. We present evidence exhibit isotropic directional dependencies scales measurement (data support), observation (extent phenomena such as dispersing plume), sampling window (domain investigation), correlation (structural coherence), resolution (descriptive detail). then...
A new statistically based approach to the problem of estimating spatially varying aquifer transmissivities on basis steady state water level data is presented. The method involves solving a family generalized nonlinear regression problems and then selecting one particular solution from this by means comparative analysis residuals. linearized error included. This allows estimate covariance transmissivity estimates as well square hydraulic head. In addition explicitly statistical orientation...
The Avra Valley aquifer in southern Arizona is modeled stochastically at three levels of uncertainty. highest level uncertainty occurs when log transmissivity estimates are based on measured values this parameter but without regard to the geographic location each measurement point. resulting steady state hydraulic heads aquifer, computed by unconditional simulation with aid a multivariate normal random number generator coupled finite element model, have relatively large variance. This...