PART 8

 

8.1. Conclusion statements

Based on environmental monitoring results in year 2007 the Nominated Monitoring Agents conclude:

1.    The key role in determining of water amounts discharged into the Danube old riverbed downstream of the Čunovo dam is assigned to the gauging station Bratislava-Devín. The average annual flow rate in this station in the hydrological year 2007 was 1768 m³s^-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 2007 it can be stated that no unusual values occurred, however the course was not typical.    
Taking into consideration obligations envisaged in the intergovernmental Agreement, the Slovak Party was obliged to release an average annual discharge of 349.2 m³.s^-1 into the Danube riverbed downstream of Čunovo dam. According to the observations carried out at the Doborgaz and Helena gauging stations, the yearly average discharge released to the Danube old riverbed downstream of Čunovo in the hydrological year 2007 was 422.9 m³.s^-1. Considering the modified method of average discharge calculation, accepted in the Joint Annual Report on the environment monitoring in 2004, discharges exceeding 600 m³s^-1, while the flow rate in the Danube was higher than 5400 m³s^-1, were reduced to 600 m³s^-1. When subtracting the amount of water over 600 m³s^-1 released during the flood events (5 values), the average annual flow rate of 393.7 m³s^-1 is obtained, which represents 112.7 % of the amount requested by the Agreement.. This means that the obligation of the Slovak Party was fulfilled. The discharge into the Mosoni branch of the Danube was 40.03 m³.s^-1, which represents 93.1  % of the agreed amount. According to the request of the Hungarian Party the flow rate in hydrological year 2007 was significantly decreased in two occasions. If these periods with decreased flow rate are not taken into the evaluation we get an annual average flow rate of 44,98 m³s^-1. Considering the technical and hydrological conditions it can be stated that the total water amount of 43 m³s^-1 envisaged in the Agreement discharged through the Mosoni Danube and through the seepage canal, was fulfilled as well.

2.    The surface water quality in the Danube in observed period was similar as in previous years. Regarding the specific hydrological and climatic conditions in the evaluated period the observed surface water quality parameters did not reach extreme values. Changes in water quality at 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. Increased values of some parameters in the Danube were related to higher flow rates in the Danube. At individual sampling sites further slight decrease was registered in case of nutrients. The dissolved oxygen content remained preserved at the level of previous years and the organic pollution was lower in comparison with the year 2006. When analysing the changes in suspended solids content at sampling sites in the Danube, it can be stated that the suspended solids content downstream of reservoir during flood waves is lower than in the Danube at Bratislava, which refer to settling effect of the reservoir. From among the heavy metals the highest concentrations were recorded in case of zinc and copper, the lowest contents were registered in case of mercury and cadmium. A large part of analysed concentrations was below the detection limits of the applied analytical methods. The fluctuation of water quality parameters in the right side river branch system follows their fluctuation in the Danube since introducing the water supply in 1995.
The water quality in the Mosoni Danube differs in the upper and lower section of the river. The water quality at the sampling site at Čunovo/Rajka follow the water quality in the Danube, while the water quality on the lower section of Mosoni Danube is formed by its affluents and local pollution from settlements. Compared to previous years the water quality significantly improved thanks to investments realised in the wastewater treatment plant, however at the Vének sampling site the highest concentrations were recorded in case of several parameters. The cleanest water was found in the seepage canals, which results from its groundwater origin.
The monitoring of hydro-biological elements of the surface water quality in the evaluated period at jointly monitored sampling sites was realised according to the new methodology. According to results the sampling sites on the Danube were classified into II. and III. quality class, which correspond to good and moderate ecological status and the sampling site on the Mosoni Danube at Vének was classified into IV. quality class, which represents poor ecological status. However, the evaluation schemes still have to be modified and finalised.    
Considering the sediment quality evaluation in 2007 it can be stated that the amount of analysed micropollutants in the influenced area is low and the vast majority of measured values were below or fluctuated closely to the Threshold Effect Level (TEL), when the unfavourable effect on biological life occurs rarely. However on the Hungarian side two exceedings of Probable Effect Level (PEL), when the unfavourable effect on biological life occurs frequently, were recorded in case of mercury. The registered concentrations in case of organic micro-pollutants mostly fluctuated below the TEL limit values.       
Comparing the water quality entering the influenced area (sampling site at Bratislava) and the water quality leaving this area (sampling site at Medveďov) it is evident, that the water quality leaving the system is very similar.

3.    Based on the evaluation of the groundwater regime 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, a significant increase in the groundwater levels occurred for low and average flow rate conditions in the Danube. A decrease in the ground water levels along the Danube riverbed can be registered for the high flow rate conditions, however in some distance from the Danube old riverbed no change was observe in inundation are and increase of ground water levels in the inland area of Szigetköz.
Regarding the atypical hydrological regime in 2007 – mostly low and average flow rates in the Danube and flood wave in September – it can be stated that the groundwater levels were lower by 0.10 - 0.60 m in comparison with the previous year. Also the water level fluctuation in the observed wells was lower. The monitoring results highlights the necessity of increasing the groundwater level in the lower part of the inundation area on both sides. The ground water level increase in the lower part of the Ásványi river branch system and in the Bagoméri river branch systems and on the Istragov Island on the Slovak side could be solved by measures applied in the Danube old riverbed.
Decreased ground water levels are registered in the strip along the Danube old riverbed on both sides. Solving of this problem need to be realised by measures in the riverbed. Any measures applied in the riverbed or in the inundation area have to conform to flood protection activities in this area.

4.    Summarizing the results of the long-term ground water quality observations on Hungarian side it can be stated that the water base of Szigetköz is typically characterised by higher iron and manganese content. The low concentration of oxygen is typical as well. The iron and manganese content exceed the drinking water quality limit values or oscillates around them in wells for drinking water supply at Győr region and permanently exceed the limits on most of the observed wells. In 2007 the contents of nitrogen form parameters and parameters indicating the presence of organic matter in general slightly decreased or it did not changed in comparison to the previous year, organic pollution is local only. Higher contents occur in wells at Győr region. The water extracted in waterworks Dunakiliti I., Feketeerdő T-II and Darnózseli I is of satisfactory quality and the groundwater quality is characteristic by high stability. In general the groundwater quality in drinking water producing wells (occasionally after pre-treatment) is suitable for a drinking water supply.     
Based on the results of the long-term groundwater quality observation on the Slovak territory it can be stated that the observed groundwater quality parameters mostly satisfies the agreed ground water quality limits. In case of waterworks exceeding of limit value for manganese was recorded at Bodíky waterworks in every sampling and once at Kalinkovo waterworks. In case of observation objects exceeding of limit values for different groundwater quality parameters occur at several objects. The groundwater quality at waterworks is stable in long term.

5.    The soil moisture content in 2007 was significantly influenced by unfavourable climatic and hydrologic conditions. Although the total amount of precipitation in 2007 was slightly higher than the long-term average, the soil moisture content till the end of August was rather low. The starting moisture content was lower than in the previous year, at most of observation objects minimal values were recorded in the layer below 1 m depth. Thanks to higher precipitation in March there was an increase of soil moisture recorded at every observation plots at the end of the month. Significant decrease was registered during the first half of June and the decrease on some monitoring areas continued until the end of August, when yearly minimum values were registered on most of monitoring sites. The decrease was stopped in September, when a flood wave occurred on the Danube. The soil moisture content increased and reached the level from the beginning of the year, at several places even higher. The development of soil moisture content till end of the year remained balanced. The soil moisture contents at agricultural monitoring sites on the Hungarian territory were mostly dependent on precipitation and weather condition. Concerning the soil moisture development at monitoring sites situated in the agricultural area on the Slovak side it can be stated that the soil moisture content and the position and fluctuation of ground water levels during the whole observed period remained unchanged. The soil moisture in the inundation area is, along with the ground water level and precipitation, highly dependent on natural or artificial floods. Generally it can be stated that the average soil moisture in 2007 was lower in comparison with the previous year. Concerning the minimal and the maximal values it can be stated that values were lower in comparison with the previous year at almost every monitoring site in both depth interval.

6.    The results of forest monitoring on the Slovak side in 2007 showed some positive changes. The growth increment of the young stands (newly planted) got remarkable better and trees were healthy. Higher values of weekly girth growth were recorded in older stands and occurrence of zero weekly increments significantly decreased. No evident reason of these positive changes was identified. The occurrence of illnesses and pests did not spread significantly after the dry and warm summer and no significant premature yellowing and defoliation was registered. In spite of positive results it should be emphasized the effective utilisation of the existing weirs in the river branch system to reach more favourable groundwater levels and the application of artificial floods. The necessity of permanent water supply to the Istragov area is constantly actual.     
The development of forest stands on the Hungarian side in 2007 was focused on long-term changes of standard increments in connection with changes of moisture conditions after diversion of the Danube. The evaluation of characteristic water levels in the Danube at Dunaremete profile before and after diversion of water shows significant decrease in average and maximal water levels. These changes were reflected in changes of increments. Analysing the increment intensity of the observed tree species it can be stated that the wood production after the diversion lag behind the wood production in the period before the diversion. The proportion on this difference of individual tree species differs, but the decrease is noticeable in case of every species. Analysing the individual age categories it can be stated that decrease of growth increment was detected for poplar “Robusta”, poplar “Pannonia” and white willow. The decrease for pedunculate oak is not significant.

7.    The development of evaluated terrestrial plant and animal communities (terrestrial molluscs) in the inundation on the Slovak and Hungarian side was remarkably influenced by periods without precipitation and with extremely high air temperatures during the summer. Flooding of the inundation area during the vegetation period did not occur. Under these conditions spreading of neophytic, weed and invasive species on both sides of the Danube (this process at monitoring areas No. 2608 and 2609 was supported by cutting off the tree layer). The most stable phytocoenoses were registered below the confluence of the Danube old riverbed and the tailrace channel on the Slovak side and along the Mosoni Danube on the Hungarian side. 
The terrestrial mollusc’s community on most of the Slovak and Hungarian sites are stabilized; occasionally they are characteristic with slight increase of antropotolerant and euryecous species. This change is significant only at two Slovak monitoring areas (No. 2608 and 2609), where the tree layer were cut off in the previous year. The large part of communities is characteristic by permanent presence of hygrophilous species.
The macrophyte communities are highly dependent on site-specific hydrological conditions. The water level in the river branch system was low, except the river arm used for water supply. In these branches (areas No. 2604, 2608 and 2612 on the Slovak side) the true water vegetation was destructed during the dry summer and spreading of marshy species was observed. The macrophyte vegetation on both sides of the Danube was similar to that in previous years. 
Concerning the aquatic fauna the aquatic malakocoenoses was relatively rich in both inundation areas. Lower species richness was recorded in the dead arm due to lower water amount (monitoring area No. 2604 on the Slovak side) and on the flood-protected area of the Szigetköz.  
The dragonfly communities in the last years were significantly poorer according to the results of the Slovak party, than the stabilized odonatocoenoses on the Hungarian side. In the evaluated year increase of species diversity can be noticed, but the presence of numerous species was proved only by flying imagines.   
On most of the Slovak monitoring areas rich Cladocera and Copepod communities occur, where the euplanktonic species dominate. Rich communities were found on the flood-protected area of the Szigetköz region, which indicate the diversity and stability of habitats. The monitoring sites in the Hungarian inundation area are in most cases slightly inhabited by planktonic crustaceans due to stronger water flow.
The occurrence of caddisflies and mayflies according to results of Slovak Party remains constantly rare and irregular in the whole inundation area. The results from Hungarian samples, which were taken in the evaluated year according to the developing methodology of Water Framework Directive, prove the presence of substantially wider spectrum of caddisflies and mayflies.
The ichtyofauna in the inundation area on the Slovak side showed higher abundance in most of the observed river arms: on area No. 2603 due to high amount of juvenile individuals, on the area No. 2604 due to excessive breeding of one expansive species. In the sub-area below the Foki weir, area No. 2608 unusually high species diversity was recorded due to multiple reconnection of the river arm with the Danube during higher discharges in previous years. The ichtyofauna was rich in species on the Hungarian side too. The most frequent were the eurytopic and limnophilous species, but in the river arms used for water supply rheophile fish species were present as well. In the flood-protected area regeneration of the fish population is observed since introduction the water supply. The species richness has stabilised and during the last several years it was balanced.    
The aquatic fauna of the Danube is prevailingly evaluated according to Slovak results in the actual year. These results show a general decrease of rheophilous mollusc, caddisfly, mayfly and fish species and retreat of euplanktonic Cladocera and Copepod species. Attention has to be paid to spreading of invasive species (mainly fish and mollusc species) on the whole Danube section. The supplemental sampling during low discharges in the Danube showed that the long-term impoverishment of communities is significantly lower than it was supposed. Many species have moved to the middle of the riverbed. The species richness of ichtyocoenoses is proved by results of the Hungarian side. 

8.2. Proposals 

Proposals given in this chapter 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.    Since the evaluation methods of ecological and chemical status of the surface water still need to be finalised in both countries the planned overview of these methods will be made in the frame of Joint Monitoring after their finalisation.

2.    Gradual extension of new surface water quality monitoring methods will be applied in case of sampling sites observed by the Parties on the Slovak and Hungarian territories. Since finalized methods for hydrobiological monitoring were not available in 2008 the monitoring including its evaluation should be considered as transitional again.

3.    The data exchange for the extended period is being finished for the surface water levels and discharges, ground water levels and surface and ground water quality. An overall evaluation of the preceding period is recommended after finalisation the data exchange.