scholarly journals Trained meta-models and evolutionary algorithm based multi-objective management of coastal aquifers under parameter uncertainty

2018 ◽  
Vol 20 (6) ◽  
pp. 1247-1267 ◽  
Author(s):  
Dilip Kumar Roy ◽  
Bithin Datta
Keyword(s):  
Coastal Aquifers ◽  
Parameter Uncertainty ◽  
Saltwater Intrusion ◽  
Management Strategies ◽  
Groundwater Extraction ◽  
Aquifer Recharge ◽  
Meta Model ◽  
Aquifer System ◽  
Multi Objective ◽  
Input Parameters

Abstract Meta-model based coupled simulation-optimization methodology is an effective tool in developing sustainable saltwater intrusion management strategies for coastal aquifers. Such management strategies largely depend on the accuracy, reliability, and computational feasibility of meta-models and the numerical simulation model. However, groundwater models are associated with a certain amount of uncertainties, e.g. parameter uncertainty and uncertainty in prediction. This study addresses uncertainties related to input parameters of the groundwater flow and transport system by using a set of randomized input parameters. Three meta-models are compared to characterize responses of water quality in coastal aquifers due to groundwater extraction patterns under parameter uncertainty. The ensemble of the best meta-model is then coupled with a multi-objective optimization algorithm to develop a saltwater intrusion management model. Uncertainties in hydraulic conductivity, compressibility, bulk density, and aquifer recharge are incorporated in the proposed approach. These uncertainties in the physical system are captured by the meta-models whereas the prediction uncertainties of meta-models are further addressed by the ensemble approach. An illustrative multi-layered coastal aquifer system is used to demonstrate the feasibility of the proposed approach. Evaluation results indicate the capability of the proposed approach to develop accurate and reliable management strategies for groundwater extraction to control saltwater intrusion.

Twenty five years of operational experience using GW modeling to evaluate sustainable use of coastal aquifers for major water supplies

2015 ◽  
Vol 10 (3) ◽  
pp. 465-473
Author(s):  
B. M. Harley ◽  
M. Gamache ◽  
K. K. Masterson ◽  
R. H. Fitzgerald
Keyword(s):  
Sustainable Development ◽  
Coastal Aquifers ◽  
Saltwater Intrusion ◽  
Large Scale ◽  
Groundwater Resources ◽  
Management Strategies ◽  
Operational Experience ◽  
Aquifer System ◽  
Southeastern Us ◽  
Groundwater Supply

The sustainable development and management of groundwater resources in coastal aquifers is complex and, historically, challenging to accomplish. Groundwater models play an essential role in addressing these complexities and providing the basis for planning future sustainable development. For more than 25 years, the authors have applied three-dimensional groundwater models to manage large scale coastal aquifers. The paper will present case studies demonstrating the application of groundwater models to evaluate conditions in complex coastal environments and to develop sustainable groundwater management strategies. These studies include Long Island, a sole source aquifer system in New York serving nearly 3 million people; aquifers in Southern California where injection barriers are used to prevent saltwater intrusion; and Savannah, Georgia in the southeastern US, where concentrated groundwater pumping has contributed to saltwater intrusion at a nearby resort island, and planning is underway to ensure a sustainable groundwater supply to both local industries and municipalities.

Application and evaluation of electromagnetic methods for imaging saltwater intrusion in coastal aquifers: Seaside Groundwater Basin, California

Geophysics ◽  
2013 ◽  
Vol 78 (2) ◽  
pp. B77-B88 ◽  
Author(s):  
Vanessa Nenna ◽  
Daan Herckenrath ◽  
Rosemary Knight ◽  
Nick Odlum ◽  
Darcy McPhee
Keyword(s):  
Coastal Aquifers ◽  
Saltwater Intrusion ◽  
Groundwater Resources ◽  
Management Strategies ◽  
Geophysical Methods ◽  
Unconfined Aquifer ◽  
Data Sets ◽  
Data Set ◽  
Aquifer System ◽  
Spatial Coverage

Developing effective resource management strategies to limit or prevent saltwater intrusion as a result of increasing demands on coastal groundwater resources requires reliable information about the geologic structure and hydrologic state of an aquifer system. A common strategy for acquiring such information is to drill sentinel wells near the coast to monitor changes in water salinity with time. However, installation and operation of sentinel wells is costly and provides limited spatial coverage. We studied the use of noninvasive electromagnetic (EM) geophysical methods as an alternative to installation of monitoring wells for characterizing coastal aquifers. We tested the feasibility of using EM methods at a field site in northern California to identify the potential for and/or presence of hydraulic communication between an unconfined saline aquifer and a confined freshwater aquifer. One-dimensional soundings were acquired using the time-domain electromagnetic (TDEM) and audiomagnetotelluric (AMT) methods. We compared inverted resistivity models of TDEM and AMT data obtained from several inversion algorithms. We found that multiple interpretations of inverted models can be supported by the same data set, but that there were consistencies between all data sets and inversion algorithms. Results from all collected data sets suggested that EM methods are capable of reliably identifying a saltwater-saturated zone in the unconfined aquifer. Geophysical data indicated that the impermeable clay between aquifers may be more continuous than is supported by current models.

Reducible Uncertain Interval Design (RUID) by Kriging Meta-Model Assisted Multi-Objective Optimization

2010 ◽  
Author(s):  
J. M. Hamel ◽  
S. Azarm
Keyword(s):  
Probability Distributions ◽  
Optimization Technique ◽  
Optimization Under Uncertainty ◽  
Upper And Lower Bounds ◽  
Multi Objective Optimization ◽  
Input Uncertainty ◽  
Meta Model ◽  
Multi Objective ◽  
Function Calls ◽  
Input Parameters

Optimization under uncertainty can be a difficult and computationally expensive problem driven by the need to consider the degrading effects of system variations. Sources of uncertainty that may be reducible in some fashion present a particular challenge because designers must determine how much uncertainty to accept in the final design. Many of the existing approaches for design under input uncertainty require potentially unavailable or unknown information about the uncertainty in a system’s input parameters; such as probability distributions, nominal values or uncertain intervals. These requirements may force designers into arbitrary or even erroneous assumptions about a system’s input uncertainty when attempting to estimate nominal values and/or uncertain intervals for example. These types of assumptions can be especially degrading during the early stages in a design process when limited system information is available. In an effort to address these challenges a new design approach is presented that can produce optimal solutions in the form of upper and lower bounds (which specify uncertain intervals) for all input parameters to a system that possess reducible uncertainty. These solutions provide minimal variation in system objectives for a maximum allowed level of input uncertainty in a multi-objective sense and furthermore guarantee as close to deterministic Pareto optimal performance as possible with respect to the uncertain parameters. The function calls required by this approach are dramatically reduced through the use of a kriging meta-model assisted multi-objective optimization technique performed in two stages. The capabilities of the approach are demonstrated through three example problems of varying complexity.

scholarly journals Managing saltwater intrusion in coastal arid regions and its societal implications for agriculture

2016 ◽  
Vol 373 ◽  
pp. 31-35 ◽  
Author(s):  
Jens Grundmann ◽  
Ayisha Al-Khatri ◽  
Niels Schütze
Keyword(s):  
Saltwater Intrusion ◽  
Saline Water ◽  
Management Strategies ◽  
Point Of View ◽  
Decision Makers ◽  
Societal Implications ◽  
Irrigated Agriculture ◽  
Natural Rate ◽  
Aquifer System ◽  
Management Interventions

Abstract. Coastal aquifers in arid and semiarid regions are particularly at risk due to intrusion of salty marine water. Since groundwater is predominantly used in irrigated agriculture, its excessive pumping – above the natural rate of replenishment – strengthen the intrusion process. Using this increasingly saline water for irrigation, leads to a destruction of valuable agricultural resources and the economic basis of farmers and their communities. The limitation of resources (water and soil) in these regions requires a societal adaptation and change in behaviour as well as the development of appropriate management strategies for a transition towards stable and sustainable future hydrosystem states. Besides a description of the system dynamics and the spatial consequences of adaptation on the resources availability, the contribution combines results of an empirical survey with stakeholders and physically based modelling of the groundwater-agriculture hydrosystem interactions. This includes an analysis of stakeholders' (farmers and decision makers) behaviour and opinions regarding several management interventions aiming on water demand and water resources management as well as the thinking of decision makers how farmers will behave. In this context, the technical counter measures to manage the saltwater intrusion by simulating different groundwater pumping strategies and scenarios are evaluated from the economic and social point of view and if the spatial variability of the aquifer's hydrogeology is taken into consideration. The study is exemplarily investigated for the south Batinah region in the Sultanate of Oman, which is affected by saltwater intrusion into a coastal aquifer system due to excessive groundwater withdrawal for irrigated agriculture.

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