Amlan Das

Application of optimisation techniques in groundwater quantity and quality management

This paper presents the state-of-the-art on application of optimisation techniques in groundwater quality and quantity management. In order to solve optimisation-based groundwater management models, researchers have used various mathematical programming techniques such as linear programming (LP), nonlinear programming (NLP), mixed-integer programming (MIP), optimal control theory-based mathematical programming, differential dynamic programming (DDP), stochastic programming (SP), combinatorial optimisation (CO), and multiple objective programming for multipurpose management. Studies reported in the literature on the application of these methods are reviewed in this paper.

Simulation of seawater intrusion in coastal aquifers: Some typical responses

Seawater intrusion in coastal aquifers is generally three dimensional (3-D) in nature. In the literature, there is a general lack of reported results on 3-D simulations. This paper presents some typical example simulations of 3-D seawater intrusion process for a specified hypothetical study area. The simulation results presented in this paper are based on the density-dependent miscible flow and transport modelling approach for simulation of seawater intrusion in coastal aquifers. A nonlinear optimization-based simulation methodology was used in this study. Various steady state simulations are performed for a specified study area. Response evaluations consider the effects of vertical recharge on seawater intrusion, effects of boundary conditions, and effects of spatially varying pumping from the aquifer. The 3-D simulations demonstrate the viability of using a planned strategy of spatially varying withdrawals from the aquifer to manage seawater intrusion. It is demonstrated that series of pumps near the ocean-face boundary induce a hydraulic head distribution that can be effectively used for controlling seawater intrusion.

Discussion of “Applying Particle Swarm Optimization to Parameter Estimation of the Nonlinear Muskingum Model” by H.-J. Chu and L.-C. Chang

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Critical Channel Dimensions for Open-Channel Transition Design

The channel dimensions leading to the critical state of flow are important in the design of channel transition. This work describes a methodology for determining the channel dimensions leading to the critical state of flow to maintain given specific energy or specific force conditions. The developed methodology works on extracting a two equal roots/factors of the specific energy and specific force expressions, where the two equal roots/factors yield the critical flow depth. The methodology is illustrated for trapezoidal, rectangular, triangular, and parabolic channels.