PART 8

 

8.1. Conclusion statements

Taking into consideration the evaluation of environmental monitoring results in hydrological year 2004 the Nominated Monitoring Agents concludes:

1.    The gauging station Bratislava-Devín plays the key role in determination of water amount discharged into the Danube old riverbed downstream of the Čunovo dam. The average annual flow rate in this station in the hydrological year 2004 was 1807 m³.s^-1, which was the second lowest annual average flow rate observed since 1992. Considering the course of water levels and flow rates during the hydrological year 2004 it can be stated that no unusual values occurred.     
Taking into consideration obligations envisaged in the intergovernmental Agreement the Slovak Party was obliged to release an average annual discharge of 356.9 m³.s^-1 into the Danube riverbed downstream of Čunovo dam. According to the observations carried out at the Doborgaz and Helena gauging stations it can be stated that the yearly average discharge released to the Danube old riverbed downstream of Čunovo in the hydrological year 2004 was 402.4 m³.s^-1. When subtracting the amount over 600 m³.s^-1, released due to technical needs of the Slovak Party (3 values), the annual average flow rate of 401.0 m³.s^-1 is obtained. According to the water management, agreed in the intergovernmental Agreement signed in 1995, the Slovak Party released 114 % of the obligated water amount. This means that the obligation was fulfilled. The discharge into the Mosoni branch of the Danube, taking into consideration the technical and hydrological circumstances envisaged in the intergovernmental Agreement, was 44.65 m³.s^-1. This means that the amount of water released to the Mosoni branch of the Danube envisaged in the Agreement was fulfilled as well.

2.    The surface water quality in the Danube in the observed period slightly improves in long-term, which is reflected in decrease of nutrient contents, COD_Mn, TOC, saprobic index and bacteria. Changes in water quality on observation points in the Danube throughout the year correspond to the water quality fluctuation at Bratislava, which is characterising the water quality entering the influenced area. The hydrological year 2004 in water quality was similar to the previous hydrological year, no extreme values of any parameters were observed. Increased or decreased values of some parameters in the Danube, seen from the long-term evaluation, were already observed at Bratislava profile, which represents the entering water quality and where the water quality of the Danube generally improved. The better surface water quality consequently influences the water quality in the territory influenced by temporary measures, realised according to the Agreement. The water quality in the main right side river branches due to the water supply follows the water quality observed in the Danube. The water quality in the spring and summer period was positively influenced by the fact that from April to September higher flow rates occurred in the Danube in comparison with the same period in the previous year.     
The tributaries and local pollution of settlements, besides the water supply influence, form the water quality in Mosoni Danube. Before the confluence with the Danube the water quality state is labile (variable in time), which is proved by unfavourable values of some parameters.

3.    Average and low water period in the second half of the hydrological year 2003 and low water period at the beginning of hydrological year 2004 significantly influenced the ground water levels in the whole area. The ground water levels decreased and on a greater part of the observed area (except the neighbourhood of the reservoir) reached the lowest or nearly lowest values since introducing the water supply. This decrease of water storage only slowly recovered. Average groundwater levels were reached from April after the surface water level increase. Highest water levels were induced after the flood wave in June. Since then the groundwater levels till the end of the hydrological year decreased again. Around the reservoir and in area influenced by water supply – in the Slovak and Hungarian river branch system and along the Mosoni Danube – the ground water level was artificially raised.     
In general it can be stated that the water supply into the right side river branch system plays an important role in influencing ground water levels over the Szigetköz region. As a result of the measures realised according to the intergovernmental Agreement significant increase of ground water levels occurred for low and average flow rate conditions in the Danube (1000 and 2000 m³.s^-1). No significant changes in the upper and middle part of the Szigetköz region and decrease of ground water levels along the Danube riverbed are proved for the high flow rate conditions (3000 m³.s^-1). The monitoring results highlights the necessity of solving the ground water level decrease in the lower part of inundation area on both sides.       
Increase of ground water levels in the strip along the Danube old riverbed on both sides could be satisfactorily ensured only by increasing water level in the Danube by measures realised in the riverbed. Such measures will improve the ground water regime in the inundation area and could also help in artificial flooding. However, these measures have to conform to the flood protection activities in this area.

4.    Summarizing the results of the long-term water quality observations of 16 groundwater quality observation wells on Hungarian side it can be stated that the water base of Szigetköz is typically characterised by higher iron and manganese content. The iron and manganese content permanently exceeds the groundwater quality limit on most of the observed wells. In 2004 the content of parameters indicating the presence of organic matter – like nitrogen forms, organic matter, presumably indicating contamination of agricultural and waste water origin – slightly decreases or it did not changed in comparison to the previous year. These changes in the water quality might reflect the integrated effect of the changes in the area, in which the changed ground water flow directions, affected by the water supply, might also play role.     
On the Slovak side it can be stated that the basic physical and chemical parameters, cations, anions and oxygen regime parameters mostly satisfies the agreed ground water quality limits at all monitoring objects. The nutrient content satisfies the agreed limits at all monitoring wells, except the ammonium ion one object. The manganese content frequently exceeded the given limits in 3 of 18 evaluated wells, while the iron concentrations frequently exceeded the agreed limits on 2 wells and occasionally on another three wells. 
In case of the wells used for drinking water supply, it can be concluded that the water quality parameters are excellent and the water composition is characterised by high stability on both sides. However, the ammonium ion and organic matter content are higher in wells in the Győr region. In these wells also the iron and manganese content occasionally exceeds the drinking water quality limit values or oscillate around them.

5.    The soil moisture content in 2004 was significantly influenced by hydrological conditions in the second half of the hydrological year 2003 and at the beginning of the hydrological year 2004. The soil moisture was positively influenced in the second half of March, when the average daily discharge continuously exceeded 2400 m³s^-1 for three weeks. The flood wave in June had further positive influence on the soil moisture and the decreasing soil moisture content was partially restored. However, since July continuous decrease of soil moisture content was recorded again. 
In the inundation area an artificial flooding in June positively influenced the soil moisture content. The amount of water discharged into the river branch system induced situations characteristic for natural floods. The average ground water level during the vegetation period 2004 was from 6 to 29 cm higher comparing the average ground water level in 2003.
According to the soil moisture observation at monitoring sites situated in the agricultural area on the Slovak side it can be stated again that the soil moisture content during the whole observed period remained unchanged.

6.    The monitored forest stands on the Slovak side consist of willow and cultivated poplars. The cultivated poplar stands are widely spread in the inundation area. The height increments on large part of the inundation area were still good, regardless the high age of trees and the absence or short connection of the ground water with soil layers. The girth growth increments decreases in last years, however the high age of trees can play an important role. The slow girth growth in 2004, without distinct growth peaks reflects the absence of floods and balanced course of the ground water level during the whole vegetation period. Actually the older stands don’t show signs of damage due to the water insufficiency, however, this phenomenon will probably cause problems at reforestation of these stands. It is supposed that the growth characteristics of young stands would be worse because of their undeveloped root system.    
The composition of forest stands on the Hungarian side is comparable to that on the Slovak side. According to dendrometric measurements in 2004 it can be stated that the middle aged and older poplar stands were affected slightly by the changed moisture conditions in the Szigetköz region after diversion of the Danube. In case of willows, the growth rate on monitoring areas with younger stands can be still considered as favourable. The increments of willow and poplar stands on shallow soils lag behind the expected growth rate. Generally it can be stated that the health state of trees in 2004 showed some stabilisation. The impact of the Danube diversion mostly affected willow stands on unfavourable locations. The health state of willows in 2004 was average, with occurrence of dry branches. Significant worsening of the willow tree health state can be observed in the region upstream Dunasziget and Kisbodak villages. With the current water supply, and due to the high calcium content in soils and the high location of willow stands most of sites became not suitable for willow growth. The health conditions of poplars show continuous improving during the last years. The unfavourable moisture conditions, especially when low amount of precipitation occur during the vegetation period, could be improved by artificial flooding of the inundation area.

7.    In 2004 no flow rate occurred in the Danube, which could evoke a significant increase of ground water level or which could flood a remarkable part of the inundation area. The ground water level was very low at the beginning of vegetation period and stayed low and rather balanced during the whole year, which negatively influenced the soil moisture conditions in the area. In June an artificial flooding of the right side inundation area was realised. The vegetation period 2004 was richer in precipitation in comparison to the previous year. This was reflected in increase of biomass of the plant layer on the monitoring areas. Significant changes in species number of phytocoenoses were not registered. The naturalness of the willow stands and the hardwood lowland in the Szigetköz exceeds the Hungarian countrywide average because of higher naturalness of the shrub and plant layer composition. Since introducing the water supply in 1995 stability in vegetation is registered along the Mosoni Danube. On monitoring areas with sufficient water supply polyhygrophilous and hygrophilous forest molluscs’ species remain dominant. In the Szigetköz region generally no appreciable changes indicating variation in the terrestrial molluscs community were recorded. The macrophyte communities are highly dependent on site-specific hydrological conditions. After the washout by the strong flood in 2002 regeneration and intensive development of aquatic macrophytes was registered in 2004. The hydrological conditions of the flood-protected area remained unchanged, so the macrophytes species compositions basically remains unchanged too. Concerning the aquatic fauna in the Danube the observation results show that the dominance of the original rheophile species decreases, while the alien rheophile species and species indifferent to the flow velocity spread. In the river branch system changes in aquatic fauna reflect the increased flow velocity. Generally it can be stated that along the water supply path the number of species rose (the number of rheophilous species increased). The species composition became stabile. Concerning the fish community in the Danube it can be stated that it has stabilised under changed condition caused by diverting the river. Decrease of the number of rheophilous species was registered, which were replaced by eurytopic species. In the right side river branch system reappearance of some rheophilous species in the ichtyofauna reflects the partial reconnection with the main riverbed. The characteristics of fish community became stable on monitoring areas supplied by water. In the flood-protected area the species richness became stable and during the last years was balanced.

8.2. Proposals

Proposals given in this point will be obligatory for both Parties and do not require further approval when the actual Joint Annual Report is approved and signed by Nominated Monitoring Agents.

1.    Concerning the average annual flow rate discharged into the Danube old riverbed the newly agreed evaluation rules will be applied since 2005. New evaluation rules are given in the Preface part of this report in the section of “Fulfilment of recommendations in the Joint Annual Report 2003”.

2.    According to the agreement of experts unified evaluation of sediment quality will be performed on 2005 sediment quality analysis data. Further attention will be given to the exact application of the agreed method in conditions of the Danube river. Cooperation of experts for surface and ground water quality will continue on improvement of the water quality data concordance as well.

3.    Further attention should be paid on revision of biological data included in the data exchange in the frame of joint monitoring in connection of approximation of EU legislation in surface water quality.

4.    In connection with the evaluation of the forest monitoring on Hungarian side the Slovak Party suggests revision of monitoring sites and data completeness. According to the suggestion No. 5 in the Joint Annual Report on the environmental monitoring in 2001 a list of new Hungarian monitoring areas had been prepared and accepted. However, no data belonging to these new monitoring areas have been provided till now.

5.    With regard to the declared unfavourable development of forest stands of significant extent in the right side inundation area the Slovak Party suggests realizing the aerial survey, focused to the evaluation of the forest health state. Results should give answer to what extent are the forest stands healthy, unhealthy or even dry. The aerial survey had been accepted as one of the monitoring method in the forest monitoring.

6.    The Parties suggest a modification of the Statute, which is necessary for changes essential for realisation of monitoring tasks of the Water Framework Directive till December 31, 2006, as well as for rationalization of the monitoring system. The Hungarian Party will submit a proposal for modification.