On the Monetary Value of an Ecological River Quality Model

A problem widely discussed in the field of water resources research is the degree of complexity a water quality model should have if it is used for water quality management. In the present work this problem is investigated by means of an example: An optimal control problem for river quality is solved for both a simple Streeter-Phelps model and a more complex ecological model. Through decision theoretical arguments it is shown how the two optimal solutions can be compared in a rational way. As in previous IIASA reports on the application of systems theory and operations research to river quality management, the methodologies described are applied to a section of the Rhine River in the Federal Republic of Germany

Mathematical Modeling of the Self-Purification of Rivers

The self-purification process in rivers is described qualitatively. Different ways of representing this process by systems of differential equations are discussed. The parameters of the differential equations cannot be measured directly. but must be estimated from experimental values of the dependent variables. For this problem, called model identification, the quasilinearization technique is recommended and explained. The technique is applied to self-purification models of some simple laboratory studies. A model is given of rivers whose benthos may be neglected. Its dependent variables are: concentration of easily degradable wastes, concentration of slowly degradable wastes, bacterial mass concentration, protozoan mass concentration, and oxygen concentration. Keeping the measurement efforts within reasonable limits, the conditions under which this model can be identified are investigated. Finally, a self-purification model of the Rhine river between Mannheim/Ludwigshafen and the Dutch-German-border is proposed. It is shown that the model is consistent with the measured data. The model is used to estimate the consequences of activities such as waste heat disposal or sewage treatment

Decision Theoretical Remark on Sensitivity Analysis

The sensitivity of dynamic systems to changes of the parameter values can be estimated by two first order methods: either by solving the sensitivity system, or by solving the original system twice with slightly different parameter values. In this paper the problem investigated is which method should be preferred in order to minimize losses due to deviations of those first order approximations from the actual sensitivity. It is shown that the method using two different parameter values is to be preferred if one is to find out whether the solution of the dynamic system could deviate from the nominal solution by more than a prescribed standard. A problem of optimal control is described for which the other method turned out to be preferable. Some other problems are mentioned for which the preferability of one of the two methods could be proved

A Methodology for Regional Energy Supply Optimization

This paper presents the essential features of a model for regional energy supply optimization. The approach proposed in the paper differs significantly from other models dealing with similar problems. These models are in most cases linear optimization models with a single attribute objective function (usually costs); other aspects such as the impact on the environment, are included in the form of constraints. The method described here attempts to include simultaneously several attributes of a certain energy supply strategy related to its economical and ecological consequences in a multiattribute utility function, which is then used as the objective function of the optimization model

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

Mathematical Modelling of Self-Purification of Rivers

The self-purification process in rivers is described qualitatively. Different ways of representing this process by systems of differential equations are discussed. The parameters of the differential equations cannot be measured directly, but must be estimated from experimental values of the dependent variables. For this problem, called model identification, the quasilinearization technique is recommended and explained. The technique is applied to self-purification models of some laboratory studies. A model is given of rivers whose benthos may be neglected. Its dependent variables are: concentration of easily degradable wastes, concentration of slowly degradable wastes, bacterial mass concentration, protozoan mass concentration, and oxygen concentration. Keeping the measurement efforts within reasonable limits, the conditions under which this model can be identified are investigated. Finally, a self-purification model of the Rhine river between Mannheim/Ludwigshafen and the Dutch-German border is proposed. It is shown that the model is consistent with the measured data. The model is used to estimate the consequences of activities such as waste heat disposal or sewage treatment

The protein puzzle : the consumption and production of meat, dairy and fish in the European Union

In het rapport 'The protein puzzle. The consumption and production of meat, dairy and fish in the European Union' brengen onderzoekers van het Planbureau voor de Leefomgeving (PBL) in kaart wat de gevolgen van de productie en consumptie van dierlijke eiwitten zijn voor milieu, natuur en gezondheid. Vervolgens schetst het PBL welke opties er in Europees verband zijn om de negatieve effecten te verminderen. Met deze studie verschaft het PBL relevante feiten en cijfers ten behoeve van het debat over eiwitconsumptie, inclusief een indicatie van de onzekerheden daarbij