PART 8

 

8.1. Conclusion statements

Taking into consideration the evaluation of the environmental monitoring results in hydrological year 2002 the Nominated Monitoring Agents concludes:

1.    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 2002 was 530.13 m3.s-1. When subtracting the amount over 600 m3.s-1, released during floods, the annual average flow rate of 419.66 m3.s-1 is obtained. This means that according to the water management agreed in the intergovernmental Agreement, signed in 1995, the obligation of the Slovak party to release the yearly average discharge, which is function of the yearly average flow rate recorded at the Bratislava-Devín gauging station, 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 42.75 m3.s-1. Taking into consideration the accuracy of measurements it can be stated, that the amount of water released to the Mosoni branch of the Danube was fulfilled as well.      
Development of the surface water levels in the Danube old riverbed during floods in March and August 2002 indicated, that the capacity riverbed significantly decreased. Measures should be taken in order to provide satisfactory flood protection of the surrounding area.

2.    Changes in water quality during the year on observation points in the Danube refer to the water quality fluctuation at Bratislava, which is characterising the water quality entering the influenced area. The hydrological year 2002 in water quality was similar to the previous hydrological year, no extreme values of any parameters were observed. The reservoir, situated downstream of Bratislava, depending on the actual flow rate and flow velocity, play certain role in settling and in removing of suspended solids. 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 tributaries and the pollution from the settlements on the Hungarian side primarily affect the water quality in the Mosoni Danube, observed at the Vének profile.

3.    According to the evaluation of ground water regime before and after realising the water supply, which was enabled by the technical measures and discharges according to the intergovernmental Agreement, signed in 1995, it can be concluded that it has caused significant rise of ground water levels on the Hungarian territory for low and average flow rate conditions in the Danube. Comparing the hydrological situation at high flow rate conditions it can be stated that the water supply did not caused a significant change in the ground water levels. In general it can be stated that the water supply play an important role in creating ground water levels over the Szigetköz region
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.    According to the long-term data evaluation on the selected 16 observation wells it can be stated that there were some changes in case of certain wells (increase of salt content at Rajka, Győrzámoly and Kisbodak, decrease at Mosonmagyaróvár; increase of iron and manganese content in the lower part of Szigetköz region, decreasing tendency of iron content continued at Rajka; some worsening concerning the organic material content at Rajka region). High ammonium ion concentration, along with nitrite, nitrate, phosphate and organic material pollution at Rajka and Ásványráró has local origin and probably comes from agricultural activity in these areas. These changes in the water quality might reflect the integrated effect of the changes in the area, in which the varied ground water flow directions, affected by the water supply, might also play role. The low dissolved oxygen; high iron and manganese concentration – sometimes above the limit value – are characteristic for the ground water of the area in general. On the Slovak side increase of manganese was detected at Rusovce and Sap, slight increase of iron occurred at Kalinkovo, decreasing tendency of nitrate content is observed at Rusovce, Čunovo and Dobrohoą». These changes are not significant and do not cause changes in the classification for drinking water supply. 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.

5.    Floods at the beginning and at the end of the vegetation period positively influenced the soil moisture formation. The average soil moisture values in the hydrological year 2002 were similar to the previous year. The soil moisture on most of the observation points on the Hungarian side was supplied from the ground water level, increased by water supply. The soil moisture of the upper part of soil layer showed a deficit of moisture due to the low amount of precipitation, especially in the middle of the vegetation period. The position of ground water level did not allow moisturising of the shallow soil profiles in the upper and middle Szigetköz. During the spring flood a large part of the inundation area was flooded; during the flood in August the water covered the whole inundation. 
The situation was similar also on the Slovak side. However, during the dry months no artificial flood simulation was done, due to damaged structures in the river branch system caused by the flood in the spring.

6.    The forest stands on the Slovak side consist of willow and cultivated poplar. The yearly increment of the willow stands in the year 2002 remained on the stabile level. The health state of the willow stands in the evaluated year remained good. The cultivated poplar stands are widely spread in the inundation area. On most of the monitoring area reached the age of cutting, but the increment values decreasing only slowly and the growing is satisfactory. Height increments on most of them still meet the curves for the I. growth class. The values of weekly girth growth measures prove the positive influence of the flood at the beginning of the vegetation period. Raising the water level in the Danube old riverbed could mitigate the negative influence of insufficient precipitation, especially during dry months in the vegetation period.      
The composition of forest stands on the Hungarian side is similar to that on the Slovak side. However, the increments of willow stands and forest stands on shallow soils lag behind the expected growth rate. The general health condition of willows was moderate, and in the area upstream Dunasziget and Kisbodak villages the health conditions show remarkable deterioration. High calcium content has been found in the soil, which can be blamed for the destruction of willow. Soils with such high carbonate content – over 20 % – can be used for cultivation of willows only in case of advantageous water supply. In the case of missing floods the stands covered by willow became not suitable for them. The health conditions of poplars show continuous improving during the last years. Thanks to the flood in August no premature defoliation was observed. The unfavourable moisture conditions, especially when low amount of precipitation occur during the vegetation period, could be improved by increasing of water level in the Danube old riverbed.

7.    The two floods in the year 2002 very positively influenced the soil moisture conditions in the area. Even on monitoring areas in the river branches area, which are under the strong drainage effect of the Danube no premature defoliation, not even mosaic loosening of coverage in the herb layer occurred. However, the eco indexes for moisture on these areas show further decrease. The herb layer was lower and the coverage smaller in comparison to the areas not influenced by the strong drainage effect. The medium and long-term impacts of floods will be noticeable in following years. On monitoring areas with sufficient water supply and favourable moisture regime changes of the phytocoenoses are not expected. The macrophyte communities are highly dependent on site-specific hydrological conditions. After introducing the water supply the river branch system became through flowing. Macrophytes settle riverbank and part with slow current of water. On most of the observed area strong wash out after the flood in August was recorded. I the flood-protected areas the development of macrophytes remained unchanged thanks to the permanent water supply and unchanged hydrological conditions. Considering the terrestrial molluscs it can be stated that on most of the monitoring sites original hygrophilous species are returning. Changes in aquatic fauna reflect the changes in the river arm system. 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. In the ichtyofauna reappearance of some rheophilous species reflects the partial reconnection of the right-side river branch system with the main riverbed. The connection of the river branches with the Danube during floods in 2002 had positive influence to the fish communities. Stable or increased species diversity and increased number of individuals was observed. The characteristics of fish community became stable on monitoring areas supplied by water. Also 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.    Because the Parties have different views on the term “flood event” the Nominated Monitoring Agents request the experts on surface water hydrology to define the term “flood” and its flow rate for purposes of evaluation of the released water amount into the Danube according to the Agreement from 1995.

2.    Regarding to the fact, that the evaluation of the surface water quality have been carried out for hydrological year and that the Hungarian Party proposed to carry out the evaluation for calendar year, Nominated Monitoring Agents requested the experts to propose and justify the period for the evaluation.

3.    The Slovak-Hungarian Transboundary Water Commission dealt with the topic concerning the differences in analytical results of surface water quality data in samples taken on common sampling points in the same time. The Nominated Monitoring Agents requested experts to evaluate applied measures and propose the further action.

4.    During the year 2003 joint verifying surface and ground water quality and sediment quality measurements will be carried out on selected sampling points on Slovak and Hungarian sides.

5.    In order to unify the evaluation of forest observation results it is necessary to continue in data collection and evaluation by using method applied in the year 2002, in case of wood yield data on the Hungarian side. By using this method it is ensured, that the yearly increment data will represent the actually evaluated year, unlike of the existing practice.

6.    For the macrophytes monitoring evaluation from 2003 the Slovak Party will use the same method as the Hungarian Party uses it. The Slovak Party will replace the evaluation according to the Braun-Blanquet method by evaluation according to the Kohler index.

7.    In the frame of biological monitoring the Hungarian Party in 2002 experimentally used a high-power output electro catching apparatus (10000 W) for fish sampling in the Danube old riverbed. Application of this method should be verified and evaluated during years 2003-2004. Based on the obtained results the abovementioned method of sampling in the Danube old riverbed, after a common agreement of experts of both Parties, could be applied in the frame of the Joint monitoring.

8.    It is necessary to attempt to identify the reason of completely different results in monitoring of Odonata, Ephemeroptera and Trichoptera. In monitoring of Ephemeroptera and Trichoptera the Parties applies different methods – the Slovak Party monitors larvae living in the water, the Hungarian Party monitors flying imagines.

9.    In case of monitoring area No. 2608 on the Slovak side it is necessary to move the monitoring sites of Odonata, Ephemeroptera and Trichoptera onto other suitable biotope inside of the original monitoring area, best, in the neighbourhood of the present sampling points.