PART 8

 

8.1. Conclusion statements

Based on environmental monitoring results in year 2008 the Nominated Monitoring Agents conclude:

1.    The gauging station Bratislava-Devín plays a key role in determining the amount of water to be discharged into the old Danube riverbed downstream of the Čunovo weir. The average annual flow rate in this station in the hydrological year 2008 was 2014 m³s^-1, which belongs to an average flow rate on the Danube. Considering the course of water levels and flow rates during the hydrological year 2008 it can be stated that no unusual values occurred. However, the course was again not typical.
Taking into consideration obligations envisaged in the intergovernmental Agreement, the Slovak Party was obliged to release an average annual discharge of 397.8 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 2008 was 426.0 m³.s^-1. According to the modified method of yearly average discharge calculation, accepted in the Joint Annual Report on the environment monitoring in 2004, no reduction of released discharge had to be done. The average annual flow rate in the Danube old riverbed corresponded to 426 m³s^-1, which represents 107.1 % 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 43.46 m³.s^-1, which represents 101.1  % of the agreed amount. No reduction of discharge was requested by the Hungarian Party in 2008. Regardless the technical (maintenance of turbines) 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 2008 was similar as in previous years and the observed surface water quality parameters did not reach extreme values. Changes in water quality at observation points in the Danube and in the river branch systems throughout the year correspond to the water quality fluctuation at Bratislava, which is characterising the water quality entering the influenced area. Basic physical and chemical parameters in the Danube and in the river branch system connected to the Danube main riverbed show seasonal variations and some of them predominantly depend on the flow rate. Increased values of some parameters in the Danube were related to higher flow rates in the Danube. The nutrients content at individual sampling sites recorded in the year 2008 was similar or slightly higher than in the previous year. The dissolved oxygen content remained preserved at the level of previous years. The organic contamination expressed by COD_Mn was lower in comparison with the previous year; however, BOD₅ values at sampling sites observed by the Hungarian Party were significantly higher, in some cases at jointly observed monitoring sites double. 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. Regarding the heavy metal concentrations, which were determined from the filtered sample, it can be stated that they were low during the evaluated year, with occasional occurrence of higher values. Great part of the determined values was below the detection limit of applied analytical methods. The highest concentrations were characteristic for zinc and copper; the lowest concentrations were registered in case of cadmium and mercury.   
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. The evaluation of the ecological status of water bodies in 2008 for individual biological quality elements was focused on sampling sites not on water bodies. According to results the sampling sites on the Danube were classified into III. quality class, which correspond to moderate ecological status and the sampling site on the Mosoni Danube at Čunovo was classified into IV. quality class, which represents poor ecological status. 
Considering the sediment quality evaluation in 2008 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 ground water 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 ground water 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 high flow rate conditions, however in some distance from the Danube old riverbed no change was observed in inundation area and increase of ground water levels in the inland area of Szigetköz. In general the overall situation is similar as in the previous year and no significant changes can be observed.    
The monitoring results highlights the necessity to solve the water supply 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 also by measures applied in the Danube old riverbed upstream of the confluence with the tail race channel. Such measures can improve the general situation in this region.
An increase of ground water levels in the strip along the Danube old riverbed on both sides could be ensured only by increase of water level in the Danube by certain measures realised in the riverbed.

4.    According to results of the long-term water quality observations at 16 groundwater quality observation wells on the Hungarian side, it can be stated that the water base of Szigetköz is typically characterised by a 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 observation wells. In general it can be stated that contents of nitrogen form parameters and parameters indicating the presence of organic matter (COD_Mn) slightly decreased or it did not changed in comparison to the previous year. The organic pollution is local, particularly of agricultural origin. The ammonium ion and organic matter contents are higher in wells at Győr region. In these wells also the iron and manganese contents exceed the drinking water quality limit values or oscillates around them, so the water is pumped from bigger depth, where the concentrations are lower. 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 manganese limit value was recorded at Bodíky waterworks in every sample and twice at Kalinkovo waterworks. In case of observation objects exceedings are more frequent and occur at more objects. The groundwater quality at waterworks is stable in long term. The groundwater quality in observation objects mostly reflects local influences.

5.    The soil moisture content in 2008 was significantly influenced by climatic and hydrologic conditions. Slightly lower soil moisture content at the beginning of vegetation period was caused by lack of precipitation during the winter. However, higher water levels in November and December 2007 well moisturized the lower part of the soil profile. Higher precipitation amount at the beginning of March partially replenished the soil moisture content. Significant influence on soil moisture content in the inundation area had the increased discharge into the river branch system. However, at the end of May the lowest soil moisture values were recorded in the upper part of the soil layers. Thanks to higher precipitation amount during June the soil moisture content increased and at most of observation sites the highest soil moisture values were recorded, but at the end of the month they decreased again. Since the beginning of August the soil moisture started to decrease and the decrease lasted till the end of October. In general it can be stated that the average soil moisture in 2008 was slightly higher in comparison with the previous year. The soil moisture contents at agricultural monitoring sites on the Hungarian territory were mostly dependent on precipitation and weather conditions. 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. In the hydrological year 2008 no natural flood occurred. However, the increased discharge into the river branch system had positive influence on soil moisture content. Generally it can be stated that the average soil moisture in 2008 was slightly higher in comparison with the previous year. Concerning the minimal and the maximal values it can be stated that values were higher as well in comparison with the previous year at almost every monitoring site in both depth interval.

6.    Based on the results of forest monitoring on the Slovak side in 2008 it can be stated that the height increment quality classification of most of forest stands remain unchanged, and reaches high level. Concerning the width increment significant improving is registered in the whole area for the second time; unambiguous reason of this is not identified. In young forest stands, which were considered as problematic after their planting, continuous improving of their state and stabilisation of growth increment is registered. Occurrence of zero weekly girth growth increments gets sporadic. The occurrence of illnesses and pests was sporadic as well during the whole growing period and no premature yellowing and defoliation was registered. The results of aerial survey focused on the forest stands health state evaluation in the whole inundation area show very good state of woodlands. The assumption of adverse effect of the Gabčíkovo hydropower structures on the forest health state was not proved. 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.    
In the actual year aerial survey of forest stands health state was performed on both sides. The survey in the Hungarian inundation was the first one, which was focused on the forest health state on large area. Evaluation of aerial survey was done in close cooperation of both sides using the same methodology. However, evaluations given in National Reports were not comparable due to several differences on the Slovak and Hungarian sides in technical parameters of aerial photographing and in evaluation as well. After re-evaluation the survey on the Hungarian side Joint Defoliation Map was compiled. Compilation of Joint Defoliation Map required unification of the level for forest health state evaluation. The evaluation on pixel level was chosen, because the boundary definition of individual forest stands on the Hungarian side (areal distribution of forest units) was not precise. Similarly, unified range for expression of the defoliation level had to be chosen as well. The ICP Forest methodology was chosen.     
Based on the Joint Defoliation Map it can be stated that the health state of softwood forest on the Slovak side is very good and the defoliation is low almost in the whole inundation area. Defoliation map of forest stands on the Hungarian side shows that the defoliation parameters are less favourable in the Dunakiliti, Kisbodak and Lipót regions, which is conform with the field results. Good state was identified in the lower part, where the backwater effect took place or at places where the soil profile reach higher thickness upon the gravel layers.
Comparing the results on the Slovak side between aerial survey in 2005 and 2008 it can be stated that results in 2008 were slightly worse than during the previous survey in 2005. However, the differences are assigned to more precise methodology of the defoliation evaluation and to improvement of the quality of aerial photos enabling to identify the defoliation on the level of individual treetops. The average defoliation in 2008 was 17.9 % with an uncertainty of ±2.3 %. The average defoliation value for deciduous forest according to the national monitoring reached 21.2 %.

7.    Although the left- and the right-side inundation of the Danube was not flooded to full extent during the vegetation period, the communities did not suffered from lack of moisture because of rather high precipitation amount. The phytocoenoses on the Slovak side are basically stabilised, occasional changes can be assigned to closure of treetops of the young tree level on individual areas. The phytocoenoses observed in the Hungarian inundation are characteristic with stable species diversity too. Neither the average leaf area values of willows and oak are changing.
The terrestrial mollusc communities on most of the Slovak and Hungarian sites are stabilised and vary in the range of levels typical from the driest to the wettest variant of the lowland forest. Occasional changes can be assigned to the impact of silviculture.
From the macrophyte communities point of view the hydro-meteorological conditions of the evaluated year were more favourable than in the previous year. In the river branches on both sides of the Danube protected and valuable macrophyte species remain preserved, more intensive spreading of invasive pondweeds (Elodea) were registered in one river branch only on both sides.       
Aquatic malakocoenoses in river branches on both sides start to show signs of instability and vulnerability. These communities depend on actual hydrological conditions, and the frequent decrease of water level linked with oxygen shortage has destructive impact on them. Decrease of species diversity and abundance can be observed, mainly on the Slovak side.
Monitoring of the dragonfly community on the Hungarian side did not show significant, tendentious changes of the stabilised odonatocoenoses. Results of the Slovak party constantly show the presence of less rich communities, however in last years larvae and imagines of more dragonfly species are recorded, ranging from rheophilous to eurytopic species.  
On most of the Slovak monitoring areas rich Cladocera and Copepod communities occur, but at areas No. 2603 and 2608 they were impoverished due to the impact of certain hydrological conditions in particular sampling dates. Frequent dominance of littoral species in the medial of several river arms can refer to an unstable environment for occurrence of these communities. The communities of planktonic crustaceans on the Hungarian side were rich, particularly in river branches on the flood-protected area. In river arms in the inundation area, where the water flow is very fast, these communities have less favourable conditions for their occurrence.
According to the Slovak results the occurrence of mayflies and mainly caddisflies remains constantly rare and irregular in the whole inundation area. The particular results from Hungarian samples, which were taken in the evaluated year according to the methodology of Water Framework Directive, prove the presence of substantially wider spectrum of mayflies and caddisflies.       
The river branches monitored on the Slovak side mostly show rather stable, rich in species and abundant ichtyocoenoses. The only exception is the river branch on monitoring area No. 2612, where situations with oxygen shortage occur or even it is drying out. Rich in species ichtyofauna was registered on the Hungarian side as well. The most frequent were eurytopic and limnophilous species, but in river branches 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 last several years it was balanced.  
The aquatic fauna of the Danube old riverbed, which is prevailingly evaluated according to Slovak results, is characteristic by changed features after diverting the river. Besides decreased participation of rheophile species (molluscs, mayflies, caddisflies and fishes) and their replacement by eurytopic species, a general impoverishment of communities is registered after the diversion. However, the degree of impoverishment is probably lower than the results show, since the rheophile species could move towards the middle of the riverbed, where they cannot be caught by the ordinary sampling methods. It has to be noticed that spreading of invasive species is registered in fish and mollusc communities on the whole Danube section.

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.    Experts on forest monitoring suggest to realize further consultations in order to improve the methodology for processing of aerial survey and for the evaluation of health state of forest stands based on aerial photographs by the date of the next aerial survey in 2011 (e.g. elimination of shadows, exclusion of non-forested areas, settling identical formulas for regression analysis, exact definition of areal distribution of forest units, improving the resolution of photographs, elimination of errors following from different intensity of neighbouring photographs, etc.)

2.    Both Parties propose expert consultations on preparation of joint evaluation of land-use and land-cover of the affected region based on satellite images.

3.    In the frame of soil monitoring the Slovak Party proposes to consider the possibility of data exchange concerning the surface and width of the soil coverage on the influence area.