Chapter 8

PART 8

8.1. Conclusion statements

Taking into consideration the evaluation of the environmental monitoring results of hydrological year 2001 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 2001 was 487.33 m³.s^-1. When subtracting the amount over 600 m³.s^-1, released during riverbed discharge capacity measurements, the annual average discharge of 436.61 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 discharge recorded at the Bratislava-Devín gauging station (428.60 m³s^-1 into the Danube old riverbed), was fulfilled. The discharge to the Mosoni branch of the Danube, taking into consideration the technical and hydrological circumstances envisaged in the intergovernmental Agreement, was 43.38 m³.s^-1. The amount of water released to the Mosoni branch of the Danube was fulfilled as well.

2. The 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 2001 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 discharge 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 discharge conditions in the Danube. Comparing the hydrological situation at high discharge 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.

4. Based on the long-term data evaluation it can be stated that some parameters of ground water quality have changed in certain observation wells due to the water supply realised on the Hungarian side: increase of iron content at Rajka and Vámosszabadi, increase of ammonium ion concentrations at Rajka, Ásványráró and Győrzámoly, decrease of iron and manganese content at Dunakiliti and Kisbodak and decrease of organic matter content in the region of Arak and Ásványráró. They are mainly connected with changes in ground water flow direction and local pollution. 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 Dobrohošť. 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. The average soil moisture values in the hydrological year 2001 were higher in comparison 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 second half 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. However, the higher water level in the Danube old riverbed during capacity measurements in March and September, increased the ground water level significantly and allowed partial moisturising of the shallow soil profiles too.
The situation was similar also on the Slovak side, but the soil moisture during the vegetation period was supplied increased ground water levels during artificial flood simulation.

6. The forest stands on the Slovak side consist of willow and cultivated poplar. The yearly increment in the year 2001 of the willow stands 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 artificial floods on some of the monitored areas, as well as the significant influence of precipitation 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 at the beginning of 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. In spite of the dry and warm August no premature defoliation was observed, except several isolated sites around Dunakiliti. 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. On some monitoring areas in the river branches area, which are under the strong drainage effect of the Danube and the water supply is not sufficient, signs of changes in the phytocoenological communities could be noticed during the last years. Moreover several areas are strongly influenced by anthropogenic impacts (cutting the forest). In general the same species remain dominant during the observation period. Only the values of dominance are changing. The drying was stopped on several sites where the introduced water supply is sufficient. However on several monitoring site there were observed higher number of species characteristic for drier biotopes. In the tree and shrub layer there were no significant changes observed in the last years. Signs of rearrangement were detected on sites affected by the drainage effect near the main riverbed; hygrophilous species are replaced by species tolerant to drier 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. The aquatic macrophyte communities are influenced mainly by the increasing water amount and flow velocity in the river branches. In this case generally the species diversity and abundance decreased. On the other side the water supply on several places ensured the spreading of original species. In the ichtyofauna reappearance of some rheophilous species reflects the partial reconnection of the right-side river branch system with the main riverbed. The characteristics of fish community have changed moderately on monitoring areas supplied by water. The species richness was stable in the flood-protected area and in the main channel of the river during the last years.

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. The experts of both Parties will carry out field documentation of surface water level observation points situated in the inundation area, which will be included in the joint data exchange.

2. The Hungarian Party in the hydrological year 2002 will provide data from three new existing surface water quality sampling points in the frame of joint monitoring. The sampling points are situated on the Danube old riverbed at Dunakiliti – rkm 1843.1 and 1842.9 (upstream and downstream of the bottom weir) and at Dunaremete – rkm 1825.

3. The experts of both Parties will study the discrepancies in the surface water quality data and will prepare recommendations for their elimination.

4. Starting from the hydrological year 2002 the evaluation of the ground water quality data observed by the Slovak Party will be done in accordance with the new drinking water standard No. 29/2002.

5. Experts of both sides in the frame of forestry monitoring prepare the list of monitoring areas available for purpose of the joint monitoring. In the frame of forest health evaluation the methodology of aerial survey should be further developed.

6. In the frame of biological monitoring the experts will continue the long-term evaluation in phytocoenology. In case of the other agreed groups of biological monitoring the jointly agreed methodology for long-term evaluation will be further developed.