Optimal Groundwater Remediation Under Uncertainty Using Multi-objective Optimization
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A methodology is developed for optimal remediation of groundwater aquifers under hydraulic conductivity uncertainty. A multi-objective management method based on a pump-and-treat remediation technology, is proposed. The pumping rates and well locations are the decision variables and two objectives are chosen: minimization of contaminated groundwater in the aquifer and minimization of remediation cost. A Monte Carlo simulation method is used to cope with hydraulic conductivity uncertainty. A number of equally probable realizations of hydraulic conductivity are created and a Pareto front is obtained using a modified multi-objective Genetic Algorithm. A penalty function is utilized to maintain the algebraic sum of pumping and recharging rates equal to zero. Since Monte Carlo simulations are CPU time consuming, a method is proposed to identify the few significant realizations which have an effect on the optimal solution (critical realizations). A Pareto front with an assigned probability is derived, so that the decision maker can make decisions with specified reliability. In a case study with 100 realizations, only 11 realizations were found critical and need be considered. The remaining 89 realizations consistently obtain low ranks for all designs considered and do not affect decisions at 95% reliability level. Thus these realizations need not be considered which implies a 89% savings in computer time. The designs obtained using the critical realizations, retain a similar reliability for new realizations not considered in the design process.
Key wordsgroundwater remediation multi-objective optimization Monte Carlo simulation uncertain hydraulic conductivity critical realizations
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- Gen M, Cheng R (2000) Genetic algorithms and engineering optimization, 495. Wiley, New YorkGoogle Scholar
- Mantoglou A, Wilson JL (1982) The turning bands method for simulation of random fields using line generation by a spectral method. Water Resour Res 18(5):1379–1397Google Scholar
- McDonald GM, Harbaugh WA (1988) A modular three-dimensional finite-difference ground-water flow model. Techniques of water resources investigations 06-A1. United States Geological Survey, Washington, DCGoogle Scholar
- Singh A, Minsker B (2003) Uncertainty based multi-objective optimization of groundwater remediation at umatilla chemical depot. In: Proceedings of the American Society of Civil Engineers (ASCE) Environmental and Water Resources Institute (EWRI) World Water and Environmental Resources Congress 2003, Philadelphia PAGoogle Scholar
- Singh A, Minsker B, Goldberg DE (2003) Combining reliability and pareto optimality – an approach using stochastic multi-objective genetic algorithms. In: Proceedings of the American Society of Civil Engineers (ASCE) Environmental and Water Resources Institute (EWRI) World Water and Environmental Resources Congress 2003, Philadelphia PAGoogle Scholar
- Wagner JB, Gorelick SM (1989) Reliable aquifer remediation in the presence of spatially variable hydraulic conductivity: from data to design. Water Resour Res 25(10):2211–2225Google Scholar
- Zheng C, Wang PP (1999) MT3DMS: a modular three-dimensional multispecies transport model for simulation of advection, dispersion and chemical reactions of contaminants in ground water systems: documentation and user’s guide. Contact Report SERDP-99-1, US Army Engineer Research and Development Center, Vicksburg, MSGoogle Scholar