The hydro-meteorological situation and events leading to the national disaster in 1940, then the record flood on the Danube in 1954 and 1965, further to that on the River Tisza in 1970 had been described in special issues together with the lessons learned from these. With the intent of continuing this tradition the particulars of the four abnormal flood waves will be presented, which had travelled down the River Tisza between November, 1998 and March, 1991.

Contrary to widespread belief, large floods are relatively rare. During the 146 years long period from 1855 to 2001 no more than 23 floods have passed down the River Tisza and her tributaries, which could be classified important or abnormal in terms of some criteria and have set milestones in the evolution of the defences in the Tisza Valley.

Major floods have always revived public interest in, and provided impetus for, flood control development. This was the case in the past centuries as well, when e.g. approval of, and the commencement of construction work on, the ambitious Tisza Valley Reclamation project was prompted by the floods of 1816, 1830 and 1845. The subsequent floods in 1855, 1867-68, 1881 and 1888, each of disastrous proportions, have re-emphasised the importance of continuing and completing the works.

The 20th century has brought no change in philosophy. The extension of flood control to the lands between the Tisza and Szamos rivers was triggered by the 1913 flood, while work on the defences along the flood plain sections in Borsod County were started after the 1932 flood (and completed in 1937). This was the last constructional measure which has reduced substantially the area of the open flood plains along the Hungarian section of the River Tisza.

The flood disaster on the Upstream-Tisza on New-Years eve in 1947-48 had direct consequences, in that it has justified the re-organisation of water management in Hungary including the nationalisation of the associations. In response to the experiences gained during the floods in 1964 and 1966 the engineering-technological level of emergency operations was improved materially. The 1970 flood in the Tisza Valley has resulted in the adoption of a new approach in the revision of the design flood levels.

The Körös floods of 1974, 1980 and 1981 have made imperative the formulation and implementation of a new development strategy of the defences, viz. the use of emergency storage.

The experiences gained during the four abnormal floods between 1998 and 2001 have been collected, arranged methodically and processed over the past two years. Compounded with these were the observations made during the extensive inundations caused by undrained runoff in 1999-2000 and the heavy local losses wrought on minor mountain streams parallel thereto.

The lessons learned from the Cyanide Disaster on the Szamos and Tisza rivers in the year 2000 and from other pollution accidents have also been assessed. The description of these events and the analysis of the experiences have been summarised in four volumes to be published as special issues of the journal Hydraulic Engineering. The first of these is devoted to the 1998 November flood on the River Tisza, the second to the events in 1999-2000, while the third to the Bereg County flood disaster in 2001.

The aim in dealing with the various floods was to follow a uniform approach comprising an outline of the meteorological situation, the hydrologic description of events, the experiences with central control, the flood phenomena observed, the course of local emergency measures taken and the assessment of the effectiveness thereof. A calendar of events is included in each volume. Articles on general and methodological issues are published in the fourth volume.

In the fifths volume terminating the sequence of special issues an attempt has been undertaken at describing the potential answers to the problems raised by the abnormal floods and the methods by which the problems of the Tisza floods can be addressed. These emergency situations present a serious challenge to the improvement of the system of defences. A review is included of the programme called “Perfection of Vásárhelyi’s Plan”, which is aimed at raising the level of flood safety in the Tisza Valley while serving at the same time the objectives of regional and rural development in its range of influence.

Without running the risk of exaggeration it appears safe to claim that the present collection of studies represents one of the most ambitious efforts undertaken thus far in Hungary at analysing and disseminating the experiences made in the field of mastering flood emergencies. The collection contains 77 articles written by 82 authors. (Several of the authors have contributed to several articles, so that the total number of authors is actually 153.)

The Editor has endeavoured to adhere to the traditions of Hydraulic Engineering. Limitations in space have, however, precluded the summaries in foreign languages. As the sole exceptions, English versions of the editor’s preface, the introduction and table of contents are included in this volume. An English summary in Vol. 5 serves to familiarise the foreign reader with the Vásárhelyi Plan.

To facilitate orientation in the various volumes, the (Hungarian) table of contents is included in each.

This is the first occasion in the history of this journal that the complete material is made available also in digital format on CD.

Floods are natural events in the regime of rivers. Rising flood levels, changes in the hydrologic parameters describing the passage of floods, the occurrence of increasingly extreme hydro-meteorological situations, the consequences of human impacts in the catchment and those of climate change must be anticipated.

Floods have been and will be inevitable features of the past and future history of the Tisza Valley. These volumes are intended to facilitate adaptation to these floods. Besides documenting the history of food fighting, the articles are expected to contribute a sound professional base to the improvement of flood safety in the region, as well as to the organisation and implementation of future emergency measures.
(Source: Special Issue of the Journal Hydraulic Engineering)

Dr L. Szlávik

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