Laszlo Somlyody

Laszlo Somlyody
Budapest University of Technology and Economics · Department of Sanitary and Environmental Engineering

Professor Emeritus Budapest Budapest University of Techology . Member of the Hungarian Academy of Sciencesy

About

76
Publications
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Publications

Publications (76)
Article
Full-text available
In the early nineties the region of Central and Eastern Europe (CEE, more than 1 million km² and 100 million inhabitants) went through fundamental political, economic and social changes which eventually led to the European integration process. This positively influenced urban water and wastewater management , which had an unbalanced structure and r...
Article
Multiobjective assessments of water resource projects are useful for widening the range of impacts that are considered during the process of project planning and selection. Some of the principles and problems associated with multiobjective analyses are reviewed, as are several relatively simple information display techniques and approaches found ap...
Article
Lake Balaton--due to its remarkable shallowness--is deemed to be sensitive to climatic variations. Historical records suggest, that the water level naturally fluctuated within significantly broader boundaries than the present regulation interval. We made a detailed, dynamic water balance simulations relying on a watershed model and two climatic sce...
Article
Aspects of municipal wastewater management in the Danube Basin are discussed with particular focus to the needs of Central and Eastern European transition countries of much lower infrastructure and economic development than Germany and Austria. The present situation of infrastructure development and nutrient emissions are discussed, which cover cou...
Article
Full-text available
The paper presents an overview about recovery of shallow Lake Balaton from eutrophication by assessing quantitative and qualitative changes in phytoplankton, zooplankton, and chironomids as a function of load reduction. The aim was to update the present water quality targets. The proposed targeting scheme supplements the existing one with a range o...
Chapter
Full-text available
The water sector has witnessed remarkable changes and developments in recent decades, and is expected to be subject to further changes. The basic issues are the increasing complexity, more attributes and their interactions to be considered, and a growing importance of the consideration of many temporal and spatial scales in parallel.
Chapter
Full-text available
In Chapter 3 the relationship between nutrient loads and lake water quality was discussed. The results obtained should now enable us to determine — at least approximately — the load reductions necessary to achieve the required level of water quality (e.g., for the lake to be shifted from a hypertrophic to a eutrophic state). We still do not know, h...
Article
Balaton is the largest shallow lake in Central Europe and the most important recreational area in Hungary. Water balance of the lake is positive, while natural water level fluctuation has been significant. In 2000, an extreme drought period started. Until 2003, water level dropped about 70 cm (about 20% of the average depth). Public concern grew an...
Article
Nutrient loads to large, shallow Lake Balaton have been reduced by 45-50% since mid-1980s. While a delayed, but still surprisingly fast recovery was observed in the hypertrophic western areas of the lake, eutrophication followed sewage diversion from the mesotrophic northern basins. We assessed factors that could lead to this unusual response. The...
Article
Lake Balaton is a large, shallow, and calcareous lake that was subject to a rapid eutrophication during the 1970s. Management measures taken from the mid-1980s decreased the phosphorus load to the lake from 0.5 to 0.3 g P m−2 yr−1. Using long-term load and water quality data, we analyse the response of the formerly hypertrophic Basin 1 of the lake...
Article
Full-text available
Successful river water quality modelling requires the specification of an appropriate model structure and process formulation. Both must be related to the compartment structure of running water ecosystems including their longitudinal, vertical, and lateral zonation patterns. Furthermore, the temporal variability of abiotic boundary conditions may b...
Article
Full-text available
In this paper, biochemical process equations are presented as a basis for water quality modelling in rivers under aerobic and anoxic conditions. These equations are not new, but they summarise parts of the development over the past 75 years. The primary goals of the presentation are to stimulate communication among modellers and field-oriented rese...
Article
Full-text available
The new River Water Quality Model no. 1 introduced in the two accompanying papers by Shanahan et al. and Reichert et al. is comprehensive. Shanahan et al. introduced a six-step decision procedure to select the necessary model features for a certain application. This paper specifically addresses one of these steps, i.e. the selection of submodels of...
Technical Report
Full-text available
ABSTRACT Successful river water quality modelling requires the specifi cation of an appropriate model,structure and process formulation. Both must be related to the compartment,stru cture of running water ecosystems,including their longitudinal, vertical, and lateral zonation patterns. Furtherm ore, the temporal variability of abiotic boundary cond...
Article
Presently the objective of urban water management is to deal jointly with water and material budgets, preferably in such a way as to establish closed cycles. The strategic analysis was made for two time horizons: For the period until Hungary joins the EU and for a longer period after that. This study analyses the strategic questions of drinking wat...
Article
Issues of nutrient management were studied in ten countries of the Danube Basin in the frame of the Danube Environment Programme. Comprehensive data collection covered socio-economic and natural factors influencing nutrient balances, water quality of the Danube and its tributaries, and major features of wastewater management for municipalities. The...
Article
Full-text available
This paper presents the major features of two decision support systems (DSS) for river water quality modeling and policy analysis recently developed at the International Institute of Applied Systems Analysis (IIASA), DESERT and STREAMPLAN. DESERT integrates in a single package data management, model calibration, simulation, optimization and present...
Article
The Hungarian watershed of the Sajó River (a shared river basin with Slovakia), representing about 5% of the country's population and territory was used as a case study to analyze issues of EU accession with special regard to drinking water supply and urban wastewater management. In the past the Sajó was one of the most contaminated Hungarian river...
Article
The Hungarian watershed of the Sajó River (a shared river basin with Slovakia), representing about 5% of the country's population and territory was used as a case study to analyze issues of EU accession with special regard to drinking water supply and urban wastewater management. In the past the Sajó was one of the most contaminated Hungarian river...
Article
Issues of nutrient management were studied in ten countries of the Danube Basin in the frame of the Danube Environment Programme. Comprehensive data collection covered socio-economic and natural factors influencing nutrient balances, water quality of the Danube and its tributaries, and major features of wastewater management for municipalities. The...
Article
Main shortcomings of eutrophication models are related to the uncertain cause-effect relations of mostly shallow, hypertrophic, blue-green algae and large internal load dominated systems. Additional difficulties emerge when these tools are used to tackle complex decision making problems, of which eutrophication may be only one element. The Kis-Bala...
Article
The Kis-Balaton reservoir system, consisting of the upper and lower reservoirs, is located near to the mouth of the Zala River. It was established for the protection of Lake Balaton against high nutrient loads. In accordance with the original plan prepared at the end of 70s the aim was that before entering the lake, nutrients - primarily phosphorus...
Article
River water quality models are used extensively in research as well as in the design and assessment of water quality management measures. The application of mathematical models for that purpose dates back to the initial studies of oxygen depletion due to organic waste pollution. Since then, models have been constantly refined and updated to meet ne...
Article
This paper is the third of a three-part series summarizing the background to and objectives of the activity of the IAWQ Task Group on River Water Quality Modelling (RWQM). On the basis of the two other papers and a comparison between the best known state of the art river model, QUAL2, and the IAWQ Activated Sludge Model (ASM) No. 1, the Task Group...
Article
The U.S. EPA QUAL2 model is currently the standard for river water quality modelling. While QUAL2 is adequate for the regulatory situation for which it was developed (the U.S. wasteload allocation process), there is a need for a more comprehensive framework for research and teaching. Moreover, QUAL2 and similar models do not address a number of pra...
Article
The U.S. EPA QUAL2E model is currently the standard for river water quality modelling. While QUAL2E is adequate for the regulatory situation for which it was developed (the U.S. wasteload allocation process), there is a need for a more comprehensive framework for research and teaching. Moreover, QUAL2E and similar models do not address a number of...
Article
River water quality models are used extensively in research as well as in the design and assessment of water quality management measures. The application of mathematical models for that purpose dates back to the initial studies of oxygen depletion due to organic waste pollution. Since then, models have been constantly refined and updated to meet ne...
Article
This paper is the third of a three-part series summarizing the background to and objectives of the activity of the IAWQ Task Group on River Water Quality Modelling (RWQM). On the basis of the two other papers and a comparison between the best known state of the art river model, QUAL2E, and the IAWQ Activated Sludge Model (ASM) No. 1, the Task Group...
Article
Main shortcomings of eutrophication models are related to the uncertain cause-effect relations of mostly shallow, hypertrophic, blue-green algae and large internal load dominated systems. Additional difficulties emerge when these tools are used to tackle complex decision making problems, of which eutrophication may be only one element. The Kis-Bala...
Article
The Kis-Balaton reservoir system, consisting of the upper and lower reservoirs, is located near to the mouth of the Zala River. It was established for the protection of Lake Balaton against high nutrient loads. In accordance with the original plan prepared at the end of 70s the aim was that before entering the lake, nutrients - primarily phosphorus...
Book
Full-text available
http://documents.worldbank.org/curated/en/1998/05/693563/municipal-wastewater-treatment-central-eastern-europe-present-situation-cost-effective-development-strategies
Article
The Kis-Balaton reservoir system, consisting of the upper and lower elements was established for the protection of Lake Balaton against high nutrient loads. In accordance with the original plan the aim was that before entering the lake, nutrients - primarily phosphorus (P) - will be removed by macrophytes. Contrary to plans, the Upper Reservoir bec...
Article
The Upper Kis-Balaton Reservoir, opened in 1985, quickly developed into a hypertrophie lake in accordance with its high P load. The original soils contained, as an average, 2% of CaCO3. The Reservoir has retained ≈50 thousand tons of calcite; mean carbonate content of the present sediments is ≈20%. A simple sediment mass balance described fairly we...
Article
Full-text available
StreamPlan was developed as an integrated, easy-to-use software system for analysing alternative water quality management policies on a river basin level. These include uniform emission reduction and effluent standard based strategies, ambient water quality criteria and least-cost strategies, total emission reduction under minimized costs, mixed st...
Article
Urbanization is definitely one of the most characteristic global changes of today and of the coming few decades. Whereas the world population grows with almost one billion per decade, around four fifths of this growth is in urban areas. The challenges due to the development of urban centers, especially great urban agglomerations in developing count...
Article
A literature review on water quality management optimization models is presented. They include linear and non-linear approaches, deterministic and stochastic methods, as well as multi-criteria decision techniques. Two river basin decision support systems, DESERT and STREAMPLAN developed recently at the International Institute of Applied Systems Ana...
Article
Global climate change related to natural and anthropogenic processes has been the topic of concern and interest world wide. Despite ongoing research efforts, the climate predictions cannot be rated any better than speculative or possible scenarios whose probability of occurrence is, at the present stage, impossible to assess. One of the most signif...
Article
Urbanization is definitely one of the most characteristic global changes of today and of the coming few decades. Whereas the world population grows with almost one billion per decade, around four fifths of this growth is in urban areas. The challenges due to the development of urban centers, especially great urban agglomerations in developing count...
Article
Industrialized countries having a large number of vehicles were suffering even in the 70's because of the undetected and non-point emissions of traffic. Emitted pollutants affected not only the quality of air, but also of surface and ground waters. The relative importance of this impact grew as waste waters had been treated. Detailed studies were c...
Article
This paper presents the implementation of one element of a decision support system (DSS) for regional water quality management, applied to the Nitra River Basin in Slovakia. A model-based, aspiration-led methodology for multicriteria decision support has been used for the study. Several reusable, modular software tools have been developed and imple...
Article
Water (and its deteriorating quality) may be the most severe stress on the exponentially growing human population in the next century. Problems are becoming increasingly complex and diverse and require more and more specific knowledge, and efficient integration across various disciplines, sectors, countries, and societies. The major challenge addre...
Article
Full-text available
This Working Paper documents the implementation of an element of a Decision Support System (DSS) for regional water quality management, applied in cooperation with the Water Research Institute (VUVH, Bratislava) and the Vah River Basin Authority to the Nitra River case study in Slovakia. Several re-usable, modular software tools have been developed...
Article
The objective of the present paper was to clarify the inconsistencies on parameters of two formerly developed resuspension models for Lake Balaton. With the aid of a new scale analysis based on the Richardson law it was demonstrated that the settling velocity of the resuspended sediment particles is primarily dependent on the hydrodynamic condition...
Article
Wind-induced sediment resuspension and its impact on the light conditions were intensively studied in three basins of Lake Balaton, a large shallow lake in Hungary, which is subject to eutrophication. The depth ranges between 2 and 5 m. Frequent observations were made of the wind, the water flows and waves, the suspended solids (ss) concentration,...
Conference Paper
Human activities have caused the C0" concen­ tration to increase steadily in the atmosphere of the Globe, the resulting "greenhouse" effect influencing potentially the future climate on global and regional scales alike. Advances have been registered in research into the meteorological and hydrological impacts of the greenhouse effect, whereas studi...
Article
Full-text available
Human activities have caused the CO2 concentration to increase steadily in the atmosphere of the globe, the resulting "greenhouse' effect influencing potentially the future climate on global and regional scales alike. Advances have been registered in research into the meteorological and hydrological impacts of the greenhouse effect, whereas studies...
Article
Field experiments were conducted in Lake Balaton, a large (surface area, 600 km2) but shallow (mean depth, 3.2 m) lake in Hungary, to quantify the resuspension and deposition of bottom sediment due to episodic storm events. Measurements were made of windspeed and direction, surface waves, mean water velocity, and suspended sediment concentration. D...
Article
Full-text available
As one of the major measures for controlling the man-made eutrophication of Lake Balaton, the Hidvég reservoir of 20 km2 surface area was built near the mouth of River Zala, draining half the watershed of the lake, and representing the largest nutrient source for the lake. The reservoir, as the first element of the expected total system of 70 km2 s...
Article
Full-text available
A stochastic optimization framework is presented for exploring cost-effective river basin water quality management strategies. The approach is based on a stochastic extension of the classical BOD-DO model which leads to a joint chance constraint on water quality. For solving the problem derived, a novel global optimization algorithm is combined wit...
Article
We develop a general framework for the study and the control of the eutrophication process of shallow lakes. The randomness of the environment variability in hydrological and meteorological conditions is an intrinsic characteristic of such systems that cannot be ignored in the analysis of the process or by management in the design of control measur...
Article
Full-text available
ABSTRACT The problem,of optimizing,a regional,water- quality,observation,network,is considered:,the,basic purpose,of the,network,is to,provide,a statistically sound,estimate,of the,annual,nutrient,load,discharged,into a lake,by its,tributaries.,Following,a brief,description of the underlying lake eutrophication problem, first a single time period,...
Article
A general class of globally convergent, derivative-free optimization procedures is presented for solving multiextremal parameter estimation problems. Following a brief description of the underlying theory, some important numerical aspects are treated. The methodology is illustrated by calibrating a model which describes an important process of arti...
Article
The issues discussed in this Executive Report are explored fully in the book "Modeling and Managing Shallow Lake Eutrophication--With Application to Lake Balaton," published by Springer-Verlag. An abstract is included under BK-86-401 in this index.
Chapter
Full-text available
Lakes act as the dustbins of their watersheds. Major fractions of materials washed out of the soil or discharged to the rivers feeding a lake accumulate in the sediments, including undesirable substances, such as insecticides used in agriculture, lead from gasoline and washed off the streets, and nutrients discharged in agricultural, domestic, and...
Chapter
In Chapter 1 we introduced the lake eutrophication problem and briefly outlined the many aspects that may play a role in the search for solutions. Obviously, the approach must cope with the characteristics of the problem, such as complexity, interdisciplinarity, and uncertainty. In addition, the approach must overcome the constant conflict between...
Chapter
The circulation of water within a lake or reservoir is an important determinant of the lake’s water quality behavior. The two major classes of motion, horizontal and vertical, significantly influence mass transport and thus water quality. Horizontal circulations are caused by the travel of water between the inflow and the outflow of the lake and th...
Chapter
Among the problems that have threatened freshwater lakes worldwide over the past 10–20 years, man-made eutrophication has been the most prominent. Eutrophication literally means “rendering rich in nutrients”. Although some lakes are naturally rich in nutrients, the term eutrophication is usually taken to mean the unintended enrichment by human acti...
Book
In the late 1970s. the adverse effects of man-made eutrophication became manifest in many countries. which explains. perhaps. why there was such a broad interest when the former Resources and Environment Area of the International Institute for Applied Systems Analysis (IIASA) organized a workshop on the subject. There was such an enthusiasm among t...
Chapter
Hydrodynamic models are often used to calculate the magnitude and direction of the wind-induced motion of water in lakes, in both engineering and water quality problems. The one- and two-dimensional model versions most frequently employed have two major parameters, the wind drag coefficient and the bottom friction coefficient. Although a number of...
Article
A systems approach is introduced into eutrophication modelling and is illustrated by the example of Lake Balaton, Hungary, one of the world's largest shallow lakes. One of the major features of the problem is its complexity. Many interrelated processes should be considered in the lake and in the corresponding watershed, both on the level of scienti...
Article
In water-quality modelling several different directions can be distinguished according to the strategy employed and the disciplinary background used for analysis. A precise classification would be difficult to make, but the manifest difference between transport-oriented and ecology-oriented water-quality models creates at least two obvious groups....
Article
Transverse mixing under steady conditions is studied by introducing the mass streamline as the streamline of the mass density vector field. The two equations derived for it allow calculations of the concentration field, or the dispersion coefficient under different assumptions if the concentrations are given. The correctness of numerical methods de...
Technical Report
Full-text available
http://webarchive.iiasa.ac.at/Admin/PUB/Documents/CP-81-007.pdf
Article
In formulating the two-dimensional mixing model for a 52 km long section of the River Danube the dispersion conditions were studied. Three tracer experiments were performed at two different streamflow rates (1900 and 1050 m3 s−1) and at constant feed. For determining the transverse dispersion coefficient a new method based on the equations of the m...
Article
In wide streams the variations in the water quality parameters are fundamentally affected by transverse mixing. Therefore using a new concept a two-dimensional mixing model was developed recently, which serves as a basis for water quality models. The use of the model is illustrated by three examples in which computed and measured concentrations are...

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