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.