Optimal Allocation of Artificial In-Stream Aeration

This paper presents some simple properties of the problem of optimal allocation and design of a system of mechanical surface aerators. These properties are proved to be valid for an extremely wide class of river quality models and it is shown how they can be usefully employed to simplify the problem and to improve the efficiency of some dynamic programming algorithms. Finally a method is suggested for dealing with the allocation problem in a river basin composed of a main stream and its tributaries

Sensitivity Analysis of Streeter-Phelps Models

Sensitivity theory is applied in this paper to a class of generalized Streeter-Phelps models in order to predict the variations induced in BOD by the variations of some parameters characterizing the river system. The paper shows how simple and elegant this technique is, and at the same time proves that many relatively complex phenomena can be explained by Streeter-Phelps models

Stable Taxation Schemes in Regional Environmental Management

Economists have frequently proposed the use of taxes to internalize externalities, the unit tax on a particular activity being equal to the marginal social damage it generates. This paper introduces such a taxation scheme, comprising a set of rules which, given a set of polluters, their profits and costs, and a Central Authority for environmental control, generates a set of taxes to be levied on the waste emissions. Different attributes of the taxation schemes are then presented, the most important of which (stability) refers to the possibility of overall cooperation between all the polluters. The paper concludes by examining the implications of the existence of stable taxation schemes and of the imposition of constraints either on the emissions or on the percentage of load removed

Uncertainty and Multiple Objectives in Storage Control Problems (A Min-Max Approach)

Analysis concerned with problems of the rational use of natural resources almost invariably deals with uncertainties with regard to the future behavior of the system in question and with multiple objectives reflecting conflicting goals of the users of the resources. Uncertainty means that the information available is not sufficient to unambiguously predict the future of the system, and the multiplicity of the objectives, on the other hand, calls for establishing rational trade-offs among them. The rationality of the trade-offs is quite often of subjective nature and can not be formally incorporated into mathematical models supporting the analysis, and the information with regard to the future may vary with time. Then the challenge to the analyst is to elaborate a mathematical and computer implemented system that can be used to perform the analysis recognizing both the above aspects of real world problems. These were the issues addressed during the summer study "Real- Time Forecast versus Real-Time Management of Hydrosystems", organized by the Resources and Environment Area of IIASA in 1981. The general line of research was the elaboration of new approaches to analyzing reservoir regulation problems and to estimating the value of the information reducing the uncertainties. Computationally, the research was based on the hydrosystem of Lake Como, Northern Italy. This paper starts a short series of IIASA publications based upon the results obtained during the study. It describes the theoretical background for the new max-min approach to analyzing multiobjective problems with uncertainties and outlines briefly some applications of the approach to water reservoir regulation problems

A Min-Max Approach to Reservoir Management

Analysis concerned with problems of the rational use of natural resources almost invariably deals with uncertainties with regard to the future behavior of the system In question and with multiple objectives reflecting conflicting goals of the users of the resources. Uncertainty means that the information available is not sufficient to unambiguously predict the future of the system, and the multiplicity of the objectives, on the other hand, calls for establishing rational trade-offs among them. The rationality of the trade-offs is quite often of subjective nature and cannot be formally incorporated into mathematical models supporting the analysis, and the information with regard to the future may vary with time. Then the challenge to the analyst is to elaborate a mathematical and computer implemented system that can be used to perform the analysis recognizing both the above aspects of real world problems. These were the issues addressed during the summer study "Real-Time Forecast versus Real-Time Management of Hydrosystems," organized by the Resources and Environment Area of IIASA in 1981. The general line of research was the elaboration of new approaches to analyzing reservoir regulation problems and to estimating the value of the information reducing the uncertainties. Computationally, the research was based on the hydrosystem of Lake Como, Northern Italy. This paper describes the application of an innovative approach to problems of reservoir management. This approach, which focuses on a risk-adverse regulation of a hydrosystem, takes into account both major aspects of this type of problem: uncertainty with regard to inflows of water into the system, and also multiple objectives which are faced by the manager. The theoretical basis of the approach has been described in another paper of this series of publications. This paper is more application-oriented, and contains also computational results for the regulation problem of Lake Como in Northern Italy

Optimal Sequencing in the Implementation of Wastewater Treatment Plants

If a set of wastewater treatment plants is to be installed in a river basin within a given time period, an interesting optimization problem is to select the best sequence in which the plants should be built. Two sequencing problems of this kind are discussed in this paper, and branch and bound algorithms are proposed for solving them. The validity of some simplifying assumptions and the effectiveness of the methods from a computational point of view are shown by analyzing the case of the Rhine river in The Federal Republic of Germany

The Management of Lake Como

This paper presents a new and heuristic approach for improving the performance of multipurpose reservoirs already in operation. The main characteristic of the method is that the analyst must first learn from the past experience of the manager and synthesize it into a very simple operating rule. Then, the analyst must point out with the help of the manager what the acceptable modifications of such a rule are. Only after these phases have been carried out can possible improvements in the management be obtained by using standard optimization techniques. The method has been applied to the case of Lake Como, (Northern Italy), and the results are quite satisfactory since the major objectives of the management can be substantially improved. The average duration of the floods on the lake shores and the mean volume of the water deficits in the downstream agricultural areas are about halved, without lowering the mean yearly electricity production of the downstream run-of-river plants. Moreover, the advantages of a revision of the active storage and of a possible protection of the shores of the town of Como are also investigated. All the results of this study had a direct impact on the management of the lake. In fact, the proposed operating rule has been programmed on a microcomputer, which is now used every day by the manager as an essential support for his final decision; the active storage was lowered in June 1982 by the Ministry of Public Works, and the sunken part of Como town will be soon repaved and elevated by the Municipality

Strategic decision making under climate change: a case study on Lake Maggiore water system

Abstract. Water resources planning processes involve different kinds of decisions that are generally evaluated under a stationary climate scenario assumption. In general, the possible combinations of interventions are mutually compared as single alternatives. However, the ongoing climate change requires us to reconsider this approach. Indeed, what have to be compared are not individual alternatives, but families of alternatives, characterized by the same structural decisions, i.e. by actions that have long-term effects and entail irrevocable changes in the system. The rationale is that the structural actions, once they have been implemented, cannot be easily modified, while the management decisions can be adapted to the evolving conditions. This paper considers this methodological problem in a real case study, in which a strategic decision has to be taken: a new barrage was proposed to regulate Lake Maggiore outflow, but, alternatively, either the present barrage can be maintained with its present regulation norms or with a new one. The problem was dealt with by multi-criteria decision analysis involving many stakeholders and two decision-makers. An exhaustive set of indicators was defined in the participatory process, conducted under the integrated water resource management paradigm, and many efficient (in Pareto sense) regulation policies were identified. The paper explores different formulations of a global index to evaluate and compare the effectiveness of the classes of alternatives under both stationary and changing hydrological scenarios in order to assess their adaptability to the ongoing climate change

Supply-Demand Price Coordination in Water Resources Management

A scheme is proposed for the coordination by prices of water supplies and demands in a region. The objective is to maximize the total regional net benefit from water use and it is achieved when the marginal benefit at each demand point is equal to the marginal cost of delivering water to that point. The class of problems to which the scheme can be applied is determined from the graph of the network connecting supplies and demands. An example is presented in which the scheme is applied to analyze possible interbasin water transfers in the Northwest Water Plan in Mexico