Reconciling simultaneous water quantity and quality aspects in drawing optimal reservoir operational strategy involves extensive computational burdens. Surrogate based optimization techniques (SBOTs) are common approaches to overcome computational bottlenecks of numerical hydrodynamic simulation models coupling evolutionary algorithm in simulation-optimization approaches. In this study, the reservoir high resolution CE-QUAL-W2 model is replaced by the lower resolution CE-QUAL-W2 and/or static ANN to speed up the optimization process. These surrogate models could consider the complex relationships to emulate the main dynamics of HR CE-QUAL-W2 model due to various reservoir operational strategies. The performance of various SBOTs, based on adaptive and sequential surrogate models coupled with particle swarm optimization algorithm, are evaluated in deriving optimal reservoir operational strategies. Then adaptive surrogate model, as the more efficient and accurate one, is applied to derive long term optimal reservoir operational strategy in the selective withdrawal scheme. The results show application of the proposed approach could enhance downstream water temperature, water demand satisfactions, and hydropower peak energy generation compared with the standard operation policy (SOP) in Karkheh reservoir during 15-year-time horizon.

This chapter contains sections titled: Classification of Heated Water Distributions and Models Proposed Models Further Work

The use of computational models for solving sediment transport and fate problems is relatively recent compared with the use of physical models. Several considerations govern the choice between physical and computational models; namely, the nature of the problem that needs to be solved, the available resources, and the overall cost associated with the problem solution. In some specific problems, a combination of physical and computational models can be used to obtain a better understanding of the processes under investigation de Vries 1973 . Using computational hydrodynamic/sediment transport models, in general, involves the numerical solution of one or more of the governing differential equations of continuity, momentum, and energy of fluid, along with the differential equation for sediment continuity. An advantage of computational models is that they can be adapted to different physical domains more easily than physical models, which are typically constructed to represent site-specific conditions. Another advantage of computational models is that they are not subject to distortion effects of physical models when a solution can be obtained for the same flow conditions identical Reynolds and Froude numbers, same length scale in the three directions, etc. as those present in the field. With the rapid developments in numerical methods for fluid mechanics, computational modeling has become an attractive tool for studying flow/sediment transport and associated pollutant fate processes in such different environments as rivers, lakes, and coastal areas. Representative processes in these environments include bed aggradation and degradation, bank failure, local scour around structures, formation of river bends, fining, coarsening and armoring of streambeds, transport of point source and nonpoint

The Environmental Effects Committee of the ASCE Energy Engineering Division has been developing a report on "Energy Production and Reservoir Water Quality" for publication. The report covers the regulatory framework that dictates much of the procedures for studies related to this topic, the fundamental reservoir hydrodynamics and water quality modeling used in preparing studies, the kinds of studies that can be prepared at different levels of analysis, and a series of applications that illustrate the problems encountered and applications of the various techniques. This study of hydrothermal modeling as applied to examining cooling tower alternatives for an existing steam electric station on a moderately large reservoir is included in this report and is presented here as an illustration of the types of studies included. This particular study subtended the usual steam electric plant cooling water discharge studies that relate to specific regulatory thermal plume size standards, and had to be designed around developing plant and cooling tower operations that would meet specific fisheries requirements for a zone of passage and refuge for fishes throughout the receiving embayment. After being used in developing cooling tower and plant operating details for the designers to work with, it was required that the hydrothermal modeling results be verified under actual tower operating conditions. In addition, it was required that the impact of the combined operations on dissolved oxygen be examined in detail. This paper covers the background to setting up the study, the kinds of statistical comparisons used to verify the hydrothermal studies, and similar studies for the analysis of dissolved oxygen distributions.

A management tool based on scientific inquiry rather than politics is needed for policy makers to make environmentally sound decisions regarding difficult issues, which will only occur more frequently as coastal populations continue to increase. Typically, a well-calibrated hydrodynamic and water quality model is used as the management tool. The development of a water quality and circulation model is based on field data that encompasses the factors affecting the water body, and the model is used to evaluate the potential effects of changing point source loadings under varying operational and environmental conditions. The level of predictability depends on the goodness of field data needed for model calibration and for setting up input data, assuming all the relevant water quality processes are simulated correctly. But there are times when good field data are available, yet the calibration is not good. In such a situation, it is conventional to revisit the algorithms used for the various water quality processes. This approach was attempted in a recent project where a three-dimensional hydrodynamic and water quality model called GEMSS was applied to predict the quality of water in the Budd Inlet, located in the Southern Puget Sound (Washington, USA). Within GEMSS, the use of the water quality model called WQDPM, which is a modified version of EPA's Eutro5 water quality model, did not predict the vertical structure of dissolved oxygen and phytoplankton at different locations in the Budd Inlet. The phytoplankton was modeled in Eutro5 as a single algal group. In order to improve the calibration, the alternate water quality model called WQCBM available in GEMSS was used. This model includes different forms of organic carbon that can be related to sediment exchange processes. WQCBM simulates five interacting subsystems: net phytoplankton production, the phosphorus cycle, the nitrogen cycle, the dissolved oxygen balance, and the particulate organic carbon balance. The carbon based model was updated to include dinoflagellates and diatoms for the simulation of phytoplankton dynamics. The ability of dinoflagellates to undergo diel vertical migration and to actively take up nutrients at night greatly improved the prediction of dissolved oxygen and chlorophyll vertical structures. The concept of using spores and cysts as primary sources for algal blooming is discussed using numerical tank simulations.

The objective of this study is to examine the influence different zooplankon grazing rate relationships have on water quality eutrophication model results in a tidal estuary. The water quality model being used includes phytoplankton and both dissolved and particulate constituents as state variables. It includes zooplankton grazing of the phytoplankton, where excretions from the latter increase the particulate constituents. The phytoplankton and particulate constituents also undergo settling. When applied to an existing estuary, the model results are different for a first order zooplankton grazing rate formulation than for a second order zooplankton grazing rate formulation.Constituents enter the estuary as wastewater discharges, freshwater river inflows, exchanges between the sediment and water interface, and exchange across the tidal boundary. The water quality model is coupled with a three-dimensional time varying hydrodynamic and transport model that allows accurate computation of the tidal velocity field transporting the constituents from their sources throughout the estuary. Comparisons of model results between the first order and the second order density dependent zooplankton grazing relationships allow determining which of the two processes best describe water quality behavior for the estuary being examined. The second order density dependent zooplankton grazing relationship performs best in application.

This one-of-a-kind workbook introduces waterbody hydrodynamic and water quality modeling techniques and the properties of different models through hands-on software. The workbook explains how to set up models for different types of water bodies and water body problems, and different ways of examining and interpreting the model results. The model software (which is included on CD-ROM) covers the circulation in water bodies as influenced by inflows, outflows, tides, winds, salinity, and temperature. Coupled with this model are a dissolved oxygen depression model, a particulate-based nutrient and eutrophication model, and a sediment scour and deposition model.

Accurate simulation of the temperature distribution in a cooling lake or reservoir is often required for feasibility studies of engineering options that increase the cooling capacity of the waterbody. A three-dimensional hydrodynamic and temperature model has been developed and applied to several cooling lakes in the south-eastern United States. In this paper, the details of the modeling system are presented, along with the application to the Flint Creek Lake.

Power plant condenser cooling water intake entrainment of fish eggs and larvae is becoming an issue in evaluating environmental impacts around the plants. Methods are required to evaluate intake entrainment on different types of water bodies. Presented in this paper is a derivation of the basic relationships for evaluating entrainment from the standing crop of fish eggs and larvae for different regions of a water body, and evaluating the rate of entrainment from the standing crop. These relationships are coupled with a 3D hydrodynamic and transport model that provides the currents and flows required to complete the entrainment evaluation. Case examples are presented for a simple river system, and for the more complex Delaware River Estuary with multiple intakes. Example evaluations are made for individual intakes, and for the cumulative impacts of multiple intakes.

Environmental regulatory agencies allow disposal of mine tailings into deep marine environments as one way of managing mine effluents. Mining companies are required to demonstrate that these Submarine Tailings Discharge (STD) systems will affect neither the quality of receiving water nor the ocean bed biota during the life-of-mine operations. A Generalized Integrated Transport and Fate model (GITF) has been developed to estimate the distribution of tailings in the near-and far-fields based on design parameters for the submarine pipeline. GITF was applied to a proposed STD serving an Alaskan gold mine. Plume dimensions were obtained from the near-field module of GITF and tailings thickness distributions were obtained from the far-field module of GITF. Sensitivity studies showed which parameters most affected the distribution of tailings; further simulations with these parameters were used to bound the results. The 3-D data visualization tool Qual View was used to display water column suspended sediment concentrations as well as sediment footprint location and thickness.

The distribution of constituents from discharges in estuaries can be determined only to the detail with which the time-varying velocity field is known. Deep estuaries can exhibit complex vertical and horizontal circulation structures depending on tides, freshwater inflows, density stratification, and geometry. A numerical, time-varying, three-dimensional hydrodynamic and transport model is applied to the Gastineau Channel, a deep estuary in Alaska, to determine the dilution of material discharged from a submerged outfall into the Channel. The ability of the model to produce realistic flow fields is first confirmed by comparing computed velocities to measured velocities for stratified and unstratified conditions. Methods are then shown for determining the flushing rate of the estuary and the distribution of dilution throughout the estuary for these same conditions.

Studies of wastewater outfalls to coastal waters are now being performed using numerical hydrodynamic and transport models. Modelling of coastal waters requires specifying tidal boundary conditions along open water boundaries. It is not possible to obtain open water tidal boundary conditions from tide height observations alone because the datum between different tide gages cannot be determined to the accuracy required for numerical modelling. Presented in this paper is a method for estimating open water tidal boundary conditions from coincident current meter and pressure sensor measurements. The methodology is applied to a numerical hydrodynamic and transport model to analyze the dilution field and rate of sedimentation around a proposed wastewater outfall into outer Saint John Harbour on the Bay of Fundy. The intermediate and far field numerical model used in this study includes the momentum of the discharge to account for near field mixing.

Port Moller is a major spawning ground for Pacific herring. Coincident with extensive larval sampling in the estuary, data required for simulating three-dimensional hydrodynamics and transport in the estuary were assembled. The three-dimensional model was used to simulate the transport of weekly larval cohorts. Different larval directed motion hypotheses were tested beginning with the simplest assumption of no directed motion through to larval directed motion into the instantaneous current with larval swimming speed as a function of larval length or age. The latter hypothesis gave the best comparison between the independent model computed results and the observed densities.

Longitudinal and vertical hydrodynamics and transport are described from the laterally averaged equations of fluid motion as shown by Blumberg in 1977, Edinger and Buchak in 1978 and 1980, and by Wang and Kravitz in 1980. The equations not only allow examining the vertical distribution of flows, but also allow examining flow properties introduced by buoyancy. Longitudinal and vertical hydrodynamics and transport apply to reservoirs and estuaries that are relatively narrow in comparison to their length and that are sufficiently deep so that stratified conditions can be established. An alternative formulation of the laterally averaged hydrodynamic and transport relationships is presented in terms of longitudinal and vertical fluxes rather than velocities and their products with various geometric averages. The formulation eliminates much of the spatial averaging of the geometry and leads to a basis for computations that more readily obtain perfect mass balances when developed to the numerical forms of the equations.