scholarly journals Joint assimilation of piezometric heads and groundwater temperatures for improved modeling of river-aquifer interactions

2014 ◽  
Vol 50 (2) ◽  
pp. 1665-1688 ◽  
Author(s):  
Wolfgang Kurtz ◽  
Harrie-Jan Hendricks Franssen ◽  
Hans-Peter Kaiser ◽  
Harry Vereecken
Keyword(s):  
Piezometric Heads

scholarly journals Complexity versus simplicity: an example of groundwater model ranking with the Akaike Information Criterion

2012 ◽  
Vol 9 (8) ◽  
pp. 9687-9714 ◽  
Author(s):  
I. Engelhardt ◽  
J. G. De Aguinaga ◽  
H. Mikat ◽  
C. Schüth ◽  
O. Lenz ◽  
...  
Keyword(s):  
Akaike Information Criterion ◽  
Conceptual Models ◽  
Information Criterion ◽  
Model Parameters ◽  
Groundwater Model ◽  
Piezometric Head ◽  
Simulated Groundwater ◽  
Pumping Rates ◽  
Uncalibrated Model ◽  
Piezometric Heads

Abstract. A groundwater model characterized by a lack of field data to estimate hydraulic model parameters and boundary conditions combined with many piezometric head observations was investigated concerning model uncertainty. Different conceptual models with a stepwise increase from 0 to 30 adjustable parameters were calibrated using PEST. Residuals, sensitivities, the Akaike Information Criterion (AIC), and the likelihood of each model were computed. As expected, residuals and standard errors decreased with an increasing amount of adjustable model parameters. However, the model with only 15 adjusted parameters was evaluated by AIC as the best option with a likelihood of 98%, while the uncalibrated model obtained the worst AIC value. Computing of the AIC yielded the most important information to assess the model likelihood. Comparing only residuals of different conceptual models was less valuable and would result in an overparameterization of the conceptual model approach. Sensitivities of piezometric heads were highest for the model with five adjustable parameters reflecting also changes of extracted groundwater volumes. With increasing amount of adjustable parameters piezometric heads became less sensitive for the model calibration and changes of pumping rates were no longer displayed by the sensitivity coefficients. Therefore, when too many model parameters were adjusted, these parameters lost their impact on the model results. Additionally, using only sedimentological data to derive hydraulic parameters resulted in a large bias between measured and simulated groundwater level.

Flow systems, tree plantations, and salinisation in a Western Australian catchment

Soil Research ◽  
1997 ◽  
Vol 35 (5) ◽  
pp. 1213 ◽  
Author(s):  
W. J. Stolte ◽  
D. J. McFarlane ◽  
R. J. George
Keyword(s):  
Rooting Depth ◽  
Tree Plantations ◽  
Medium Term ◽  
Element Analysis ◽  
Saline Groundwater ◽  
Flow Mechanisms ◽  
Piezometric Heads ◽  
Vegetation Species ◽  
Western Australian

A lower hillslope in the Western Australian wheatbelt had become waterlogged and saline by 1981, when close-spaced rows of eucalypts were planted in blocks both in and adjacent to the discharge area and piezometers were established on the site. We analysed the trends in the piezometric heads and salinity concentrations over the period of record. We also modelled the hillslope profile using finite element analysis to determine the water flow mechanisms and to see how a change in vegetation in the upland area would affect the waterlogging and salinity. Piezometric levels under the trees decreased for the first 5 years after planting and then stabilised until 1991 when they started gradually decreasing again. The non-treed area between the plantation blocks remained unaffected until about 1991, when the levels there also started to decrease quite significantly, probably because of the trees. The trees therefore appear to have been effective and beneficial in the short to medium term. However, the salinity of the groundwater under the trees has increased significantly in the last 5 years, particularly where the tree density is highest. The continued flow of saline groundwater to the trees is believed to be increasing the salinity. It could not be expected that plantations of this type will maintain health and be able to control the excess water in such an hydrologic setting in the long term. Tree plantations on discharge areas are a short to medium term management strategy, not a solution, and the only way to control salinity in the long term is to plant vegetation species in the recharge areas that use all of the water that falls there. Modelling showed that only a small surplus of water over winter, in the order of 50 mm/year, caused the increased recharge and consequent salinisation. The modelling results also show that the surplus could be managed with an effective vegetation species (e.g. lucerne) with a rooting depth of about 1·5 m that would be able to transpire at least until early to mid summer.

Evaluation of pond/aquifer flow exchanges using local discretization and contrasting different boundary condition in MODFLOW. Case of Santa Olalla pond (SW Spain)

2020 ◽  
Author(s):  
Carmen Serrano-Hidalgo ◽  
Javier Heredia Díaz ◽  
Carolina Guardiola-Albert ◽  
Francisco Javier Elorza Tenreiro
Keyword(s):  
Regional Scale ◽  
Numerical Representation ◽  
Grid Refinement ◽  
Local Grid Refinement ◽  
Natural Park ◽  
Steady State Model ◽  
Strategic Location ◽  
Local Grid ◽  
Piezometric Heads ◽  
Regional Aquifer

<p>Almonte-Marismas is a coastal aquifer situated in Doñana Natural Park (Southwestern of Spain, Huelva). It supports one of the most important wetland areas in Europe due to its biodiversity, size and strategic location. Nowadays, the aquifer suffers serious threats due to the large amount of water extraction that takes place in the area due to the high demand for water that exists for the supply of tourism and irrigation.</p><p>There is a flow model of the regional aquifer which is used to support the water management Administration. However, this model does not take into account groundwater interactions with local ponds. Santa Olalla pond is a hypogenic wetland that, on a regional scale, it receives the discharge of the Almonte-Marismas aquifer. This fact allows it to maintain a permanent water regime without suffering a reduction in its volume of water. Despite of that, the intense pumping in the zone could affect it and be a risk in the future.</p><p>The objective of this study is the identification of an appropriate model structure to characterize and implement the Santa Olalla Pond in the current steady-state model of the regional aquifer of Doñana employing ModelMuse interface. For this purpose, different boundary conditions (LAKE and DRAIN packages) were contrasted to represent the pond, combined with different local grid refinement (LGR2 package). The contrast criteria to assess the goodness of the numerical representation have been the piezometric heads in the wells situated in the surroundings of the pond and the stage levels and water balance of the pond.</p>

scholarly journals Piezometric Assessment for Salinity in Multi Aquifer System in Dharoi Command Area, Gujarat

2019 ◽  
Vol 8 (6) ◽  
pp. 945-951
Keyword(s):  
River Basin ◽  
Shallow Aquifer ◽  
Command Area ◽  
Aquifer System ◽  
Water Logging ◽  
Sabarmati River ◽  
Sensitive Parameters ◽  
Piezometric Heads

Our earlier study carried out in Dharoi command area in Sabarmati River Basin, in India, defined the sensitive parameters to address the problem of water logging and salinity in the shallow aquifer, contribution of multi-aquifer system in making the scenario complex, was thus evident. Therefore, extension of the study by analyzing the piezometric data of complex lithological setup is attempted in this paper. The present paper establishes and discusses the relationships of various depth wise aquifer zones with the help of the seasonal piezometric heads and TDS values, analyzed as tracers.

scholarly journals OPTIMIZED AQUIFER MANAGEMENT, USING LINEAR PROGRAMMING.AN APPLICATION TO THE AGIA VARVARA AQUIFER, DRAMA, GREECE

2013 ◽  
Vol 7 (3) ◽  
pp. 395-404
Keyword(s):  
Linear Programming ◽  
Water Mass ◽  
Response Matrix ◽  
Difference Model ◽  
Monthly Basis ◽  
Aquifer Management ◽  
Flow Rates ◽  
Optimal Values ◽  
Water Mass Balance ◽  
Piezometric Heads

The present research analyzes the behavior of Agia Varvara aquifer in Drama, Greece. A comprehensive and complete simulation-management combination model is applied, capable of calculating the water mass balance of the aquifer and defining the optimal management solution. In order to simulate the aquifer, a finite difference model is used. By applying this model and the Response Matrix Method, the management of the aquifer is achieved. Once the simulation of the aquifer is finished, the Linear Programming analysis is performed to obtain the optimal values of piezometric heads and flow rates, imposed to the system on monthly basis, in order to meet the demand of water at the lowest cost. The resulting piezometric heads are compared with the initial ones, enabling scenarios about the maximum and minimum drawdown, and providing the critical months of irrigation. The Linear Programming is used to facilitate the operation of systems, maximizing the total amount of pumped water, under a given set of constraints.

Finite difference modelling of the variation in piezometric head within a rockfill embankment

1991 ◽  
Vol 18 (2) ◽  
pp. 254-263 ◽  
Author(s):  
Ronald D. Townsend ◽  
Vinod K. Garga ◽  
David Hansen
Keyword(s):  
Finite Difference ◽  
Difference Scheme ◽  
Finite Difference Scheme ◽  
Darcy Flow ◽  
Flow In Porous Media ◽  
Piezometric Head ◽  
Waste Dumps ◽  
Hydraulic Gradients ◽  
Flow Through ◽  
Piezometric Heads

The subject of flow through rockfill is of increasing interest in Canada. Rockfill drains are presently used by mining companies in order to permit existing creeks to flow through the base of mine waste dumps. There is potential for the use of flow through rockfill dams for mini-hydro schemes because the adoption of a costly concrete spillway may be unnecessary in some cases. An important issue in the design of flow through rockfill structures is the pore pressure distribution and the associated hydraulic gradients, neither of which are associated with Darcy's law. For such determinations the finite difference scheme of Curtis and Lawson, which is based on the partial differential equation presented by Parkin et al., was investigated. However, expressions for edge nodes under this non-Darcy finite difference scheme do no exist. This paper presents the effect on the results of using more direct expressions for the edge nodes. Analytical results are compared with observed piezometric heads in the case of two model flow through rockfill dams. Further, it is shown that through the use of a standard electronic spreadsheet, piezometric heads for non-Darcy flow in porous media and the associated hydraulic gradients can be modelled directly without the need of complex computer programming. Key words: flow through rockfill embankment, piezometric head, finite difference method, non-Darcy flow.

scholarly journals Hydrogeological Study of the Glacial—Fluvioglacial Territory of Grandate (Como, Italy) and Stochastical Modeling of Groundwater Rising

2018 ◽  
Vol 8 (9) ◽  
pp. 1456 ◽  
Author(s):  
Ivana La Licata ◽  
Loris Colombo ◽  
Vincenzo Francani ◽  
Luca Alberti
Keyword(s):  
Threshold Level ◽  
Automatic Calibration ◽  
Underground Structures ◽  
Site Model ◽  
Code Model ◽  
Hydrogeological Study ◽  
Model Independent ◽  
Piezometric Heads ◽  
Hydrogeological Structure ◽  
Monthly Probability

On November 2014, the Municipality of Grandate, near Lake Como, had to deal with a great emergency that was caused by the flooding of factory undergrounds. The authors realized a hydrogeological study to understand the causes of groundwater flooding and to prepare a pre-feasibility study concerning possible actions for groundwater control. The hydrogeological structure is rather complex and required time-consuming reconstruction of the conceptual site model. A transient numerical model was developed to analyse the system behaviour in different scenarios. The flow model was calibrated in a steady and unsteady-state using the automatic calibration code Model-Independent Parameter Estimation (PEST). The study demonstrated that the reason for floods was mainly due to the concurrence of three causes: (1) the hydrogeological structure of the area was recognized as a stagnation zone, (2) groundwater rising, and (3) extremely heavy rainfall in 2014. Through the PEST RandPar function, 100 random rainfall scenarios were generated starting from rainfall data for the last 20 years. The model was used to run 100 1-year long simulations considering the probability distribution of recharge related to the 100 randomly generated rainfall scenarios. Through collecting the piezometric heads that resulted from the simulations, monthly probability curves of groundwater exceeding a threshold level were obtained. The results provided an occurrence probability of groundwater level exceeding the underground structures level between 12% and 15%.

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