It was on the day of April 19th 1995 that an Agreement was brought about between the governments of Slovakia and Hungary in favour of the provisional water-recharge of the Szigetköz. According to the Agreement emissaries of the two parties – i.e. the deputy state secretary in charge of environment protection on the Hungarian side and the government’s commissioner dealing with issues connected with the Gabcikovo Project on the Slovak – accepted a Statute the 29th of May 1995, devoted to the activities of the persons commissioned to operate the instruments measuring discharges and to take technical measures in compliance with the Agreement. The Statute contains statutory provisions concerning the measuring-observing activities of the parties, as well as about the exchange of data and the annual reports, documents to be compiled each year.

The present conference is aimed at summing up the results of the ten years long monitoring carried on by the two parties. It is not only the round anniversary that may be a reason for such a summary; the main aspect is to give a clear picture about the work accomplished both for professional bodies and for citizens, wanting to know more.

In the long years of monitoring a great deal of knowledge and valuable experience has been collected, about environmental procedures, which – in some of the cases - are unparalleled in the whole of Europe. In the impact area of the Gabcikovo Dam major hydrological changes have manifested themselves and succession procedures also accelerated. Water recharge towards the Szigetköz is aimed at counterbalancing disadvantageous effects of the diversion of the Danube. The common monitoring is expected to keep track of the effects of water recharge. We shall see, that procedures evolving cannot be evaluated with a single yes/no decision. Talking about their results lecturer shall equally give account of advantageous and disadvantageous features.

It is deemed to be a positive feature in the eyes of both of the parties, that exchange of data has been going on during the last ten years in a good order, national and joint annual reports were edited year-by-year according to the regulations, and that factual data on the environmental impacts, as well as evaluation of them were invariably incorporated in these reports. Experts of the two countries did not only strove for thick volumes of books to be published, for efforts were also made to render availability of their knowledge accessible by means of the Internet.

After that much time devoted to the problem the question, if a modification of the regulations was necessary at all does inevitably emerge. Insisting upon stability and permanence is though a basic property of environmental monitoring programs still we have to give due consideration to the question, whether data base such generated would equally satisfy obligations which we have taken upon ourselves, if judged according to European norms.

There are, as it is, three guiding principles of the EU accepted by both countries, all three effecting our monitoring work in future. The framework principles of water management call for the introduction of new rules in respect of water quality measurements. Criteria of the Natura 2000 approach call for a switch-over as regards observations of the world of living creatures, since flood plane woods of the region qualify now as one of the habitats to be protected. And – last but not least – we shall come forward with a modification proposal concerning exchange of data and evaluation documents (and this in the spirit of the principle prescribing a free access of the public to data of an environmental character): all data should be accessible for anybody in an up-to-date (digitalised) format as one of the basic human rights.

We sincerely hope that a discussion about our proposals for changing the Statute shall be started with as with a part of the agenda of the Conference.

An efficient operation of the recharge system of the Szigetköz was rendered possible by the building of the bottom sill. The recharging system has a fundamental aim to save nature protection values obtained its operational water permit in 2001. Regulations, serving as a basis for the operational order were prepared by the North-Transdanubian Environmental and Water Directorate also involving the public in the composition of that. Operation of this system shall be evaluated by the Szigetköz Operational Committee assembled annually with the participation of all interested parties. The paper exposes major characteristics of the recharging system, describes the methodology of actual recharging and highlights fundamental principles adhered to. A few thoughts are given to the monitoring system, which does also participate in the evaluation of the operational order.

The Szigetköz Landscape Protection Area is – beside the Duna-Dráva National Park, extending over Gemenc–Béda–Karapancsa – the second largest protected area of the Hungarian stretch of the Danube and the third largest along the whole length of the river. Unfortunately, a series of valuable habitats were left unconsidered at the time when protection of the park area was declared. Swampy meadows, marshlands, gallery forests left out of the Park area shall probably be placed under protection when a general enlargement of the area, - a move to take place sometimes in the years ahead of us - shall actually be accomplished. As it is however, the Szigetköz Nature 2000 area (the one to be introduced by the present lecture), has taken shape on the basis of habitats of special value from the point of view of nature protection, and this through the amalgamation of the area of the existing nature protection park with the territory of the envisaged extension area and with the surrounding lands, also satisfying the guidelines of the Habitat Protecting Principles of the EU.

Exploring hydro-morphological conditions and tracking their dynamic change has been an important issue in the past decade in Szigetköz area. As such changes are driven by hydrodynamics in various flow regimes, high resolution flow measurements and numerical modelling are essential to understand the phenomena and estimate the impact of the modifications in the river bed or flood plain land use. The talk focuses on presenting the 2- and 3D flow models recently implemented for the Szigetköz area including the main channel, the floodplains and the system of secondary branches both in Hungary and Slovakia. Model results calibrated against field data and their utility in assessing various natural changes or man-made interventions will be shown.

Closing the main channel of the Danube in 1992 and diversion of a decisive part of the discharge towards the upstream channel of the Gabcikovo Hydropower Plant has fundamentally changed the channels of the Danube and those of the branch systems, as well as the runoff conditions of the riverflow. Results of the surveys (riverbed topography and bed material analyses), carried out repeatedly since the diversion of the river have confirmed, that the “maintenance discharge” provided causes adverse sedimentation processes in the main Danube channel and in the Szigetköz branches, disturbing the connection of surface and subsurface waters and generating drastic changes of the water conveyance (bed roughness) conditions.

Considering the entire Szap- Rajka section of the Danube, significant narrowing of the river channel, development of side bars and a rather dense and tall vegetation over them have occurred. The riverbed surveys showed that the area of the river channel decreased by 410 hectars, i.e. by 33 % compared to the one before the diversion.

According to the results provided by the control of channel changes of the Szigetköz Branch systems since 1992, the governing bed morphological process has been the aggradation. E.g. the channel of the Bagomér branch, denoted as a sediment trap has lost 346 000 cubic-meters of its original volume equalling to a specific filling-up of 60 cm. The uppermost 15-20 cm thick layer of this aggradation consists of silt.

Surface and subsurface water-level measurements are carried on in the Szigetköz by several institutions. Summarising data from time to time is a commanding necessity, also in order to have a clear picture about the tendency of changes of measured parameters in time, about their territorial distribution and also in order to sum up different statistical characteristics of this vast quantity of data. The Environmental Protection and Water Management Research Institute has been involved in this activity for several decades by now; and called – a couple of years ago - a data base into being, one, that can also be used as an information system.

The paper makes one familiar with the changes of ground water table, supported there by time/data diagrams and contour maps plotted on the basis of a data bank initiated 50 years ago. Interdependencies between these and other types of data, with emphasis laid upon the relationship between these and the level of surface waters in the area.

The theme "Elaboration of a ground-water management concept for the Austrian, Slovakian and Hungarian border area" was dealt with within the frames of a Phare project, aimed at investigations of groundwater movements in the Szigetköz, and at the exposition of recharging procedures launched in order to restore the equilibrium state of the balance of subsurface waters.. One of the results was the elaboration of a non-permanent 3D hydrodynamic model of the area. This has been brought into being in three versions, notably for the conditions prevailing before and after the diversion of the Danube, and for the second variant “after diversion” but also reflecting the effects of the water recharging system of the flood area also in operation. Processing geological and hydro-geological data took place – beside the traditional graphical method – by means of geo-statistical methods as well, with a final 3D model constructed by the use of parameters such obtained.

Authors shall brief the audience about the geo-statistical method applied and the results obtained after processing data. Structure of the 3D hydro-dynamical model shall be explained by and large, this followed by the presentation of the main directions of the ground water recharge system of the Szigetköz determined by means of modelling for the three situations tested, with the water-balance of the area also presented.

It is since the year of 1992, that the North-Transdanubian Environment Protection, Nature Conservation and Water Inspectorate, Győr was appointed to operate the Upper-Danube Environmental Observation System (hereinafter Danube Monitoring). Construction works on the Project were started with in the year of 1986.

The water quality control network operated in the Szigetköz does actually integrate all of the sampling points of the national network, and – in addition to that – all the 11 sampling places of the Hungarian-Slovak inter-governmental monitoring agreement, that had been concluded some time ago to improve the water supply of the flood planes and to promote the case of the water recharge to the Mosoni-Duna.

In case of surface waters the survey program extends over the waters of the Szigetköz flood area and of the protected area, as well as over the 35 sampling stations of the Mosoni-Duna and its tributaries where regular monthly (in case of reference stations two-weekly) physical and chemical analysis take place. Scope of parameters thus tested includes indicators of salt balance (anions and cations), oxygen household, indicators of nutrients and some of the micro contaminants.

Hydro-chemical conditions of water bodies can be reliably characterised by means of processing test results of the last ten years, also establishing the measure (degree) of contamination through these means. Results of the analysis of riverbed sediments throw light on the extent to which the accumulation of polluting agents has actually advanced.

A series of tests was continued within the frames of the program “Hydro-chemical and Hydro-biological monitoring at the Surveys of the Szigetköz Water-recharging System” in the years of 2002 – 2005 on a regular monthly basis with analyses aimed at detecting water-quality characteristics as follows:

Water temperature and meteorological conditions were invariably recorded on each occasion. In addition to that dissolved oxygen concentration and Secchi-transparency was measured at the sampling point. The pH value of water samples was again measured in case of each sample delivered to the laboratory, together with the conductivity coefficient and chlorophyll-concentration. As for filtered water-samples parameters as follows have again been determined: total of ammonia, free ammonia and quantity of dissolved reactive phosphorous.

In the year of 2004 concentration of phosphorous retrievable for algae was determined in the bottom sediment of the river branches.

The lecture shall give account of the investigation and about the results obtained through them.

The authors present the monitoring activity of the Geological Institute of Hungary (MÁFI) and Environmental Protection and Water Management Research Institute (VITUKI) executed during the last 10 years. Emphasis is laid upon locations with dense investigation network and also on the methods applied. The observed hydrochemical changes are interpreted according to the following aspects:

Apart from the monitoring results the chemical state is presented on the basis of the work prepared for the 2005 National Report of the EU Water Framework Directive as well, considering all subsurface water quality data available for the water body. Additionally, the related part of the evaluation according to the EU Nitrate Directive will also be presented.

Regional assessment will be accomplished according to the following groups with special emphasis on the quality of the recharge water:

The pertinent figure indicates the observation points, whereas the table summarises the components tested and the results of the tests, grouped according to the most typical changes.

Weeds are part of the flora of Szigetköz, part of the diversity of it. They have an important role in the maintenance of the multi-colouredness of the living world, and this in spite of the economical damage caused by them. Changes in the moisture content of the soil are indicated by weeds as well as by any other elements of native flora or by cultivated plants. Due to this they serve as a useful indicator system for plant growing over the impact area of them and also for nature protection efforts over this same area.

The Department of Botany does investigate the features of changing of weeds since the diversion of the Danube.

Investigations like that are carried on in all of the three regions of Szigetköz, with 7 – 7 permanent observation area in all of the regions. Surveys do actually take place on plots sown

with corn and wheat, or over ruderal areas. Repeated surveys are accomplished invariably in the autumn. Extensive and intensive cultivation areas are separately evaluated.

The paper acquaints the audience with the results of the survey and analysis of the weeds.

Moisture content of soils is measured by the Szigetköz Research Centre of the University at 30 stations. 23 of the stations are located on the protected side (22 of these over farmlands, 1 in a forest), with the remaining 7 situated in forests of the flood area. Number of annual surveys is 17 on an average. In the growth season surveys are performed with 14 days intervals, out of that though once a month only. Final data obtained is the total of moisture content in the vertical line, with measurement at every 10 cm interval.

The water quantity rise - through capillary movement - from the ground water up to the overlaying soil strata plays in the Szigetköz a very important role in the water balance of soils. Diversion of the Danube resulted in the sinking of the ground water table. In areas where the ground water table sunk to depths below the overburden this effect of moisture content enrichment got interrupted, a feature unquestionably proved by the regular measurements. Measures taken after the diversion of the Danube could not counterbalance this effect and failed to increase the groundwater level to the original heights. Lecturers shall demonstrate the modification of the moisting effect of the ground water through. data obtained at the survey spots at Rajka, Halászi, Dunasziget and Ásványráró in the year of 2002.

It was in the year of 1991, that Hungarian Danube Research Station, Institute of Ecology and Botany of the Hungarian Academy of Sciences actually started with regular, monitoring-like hydro-biological surveys in the waters of Szigetköz, - whilst their own previous investigations reach back as far as the sixties of the previous century. The primary goal of the systematic monitoring work of more than a decade was the characterisation of the basic hydro-biological status of the waters surrounding the Szigetköz, with special attention paid to the identification and evaluation of environmental effects connected with operation of the Gabcikovo Dam. Our research was aimed from the very beginning at the chemical properties of the water (and of the sediments thereof), the phytoplanktons (and at the trophity level of them), at the zooplanktons of the riverside stripe of the bed, such as mezo- and macro-fauna of invertebrates, at the stock of macrophytons, as well as conditions of fish population and biological circumstances of fishing. Surveys at almost 40 locations - in the main branches of the Danube, at side channels over the flood area, at water bodies along the protected side of the levees and – partially – along the Mosoni-Duna - were successful, in that they pointed out the sensitive, occasionally more enhanced changes of communities of aquatic organisms as corresponding to the changes of their living conditions.

Results of the monitoring enriched our knowledge with valuable teachings about the long-time dynamism of the groups of living organisms subject to our observations. Due to this we are in the position today to evaluate efficiency as well as certain shortcomings of the investigation with a great deal of experience to rely upon. Our hydro-biological research work has altogether yielded a clear evidence about the outstanding natural values of the water-bodies of the Szigetköz - also displaying a great biological diversity – about the direct damaging effects of the diversion of the Danube, about the consequences of measures aimed at the mitigation of damages, and about the standardisation, homogenisation procedure obviously taking place in the aquatic organisms at present. Data such obtained do however not fully satisfy latest information requirements, like those of the rehabilitation program of the water system of Szigetköz, or of the ones, which shall necessarily accompany the introduction of the framework guiding principles of the EU on water policy. It was under these circumstances, that the Hungarian Danube Research Station, Institute of Ecology and Botany of the Hungarian Academy of Sciences made preparations for the review of their monitoring strategy and for the definition of the general line of development, not loosing sight off latest international results in respect of the methodology of hydro-biological research of great rivers, and concerning the activity taking actually shape in the fields of water-basin management.