II. Agreement between the Government of the Slovak Republic 

and the Government of Hungary 

about Certain Temporary Measures and Discharges to the Danube and Mosoni Danube, 

signed on April 19, 1995

Dominik Kocinger, Zoltán Hlavatý 

The specifications of water management measures according to the “Agreement” [1] are:

• Increase the water discharge into the Mosoni Danube from 20 to 43 m³/s via the Čunovo intake structures, under certain assumptions of hydrological and technical conditions as specified in the "Agreement" and via the right side seepage canal.

• Distribute this water on the Hungarian territory into the river branches on the right side of the Danube, into the protected area, and into the Mosoni Danube branch.

• Increase and regulate discharges into the main Danube, downstream of the Čunovo weir, between 250 and 600 m³/s  - 400 m³/s in yearly average - according to rules specified in the annexes to the "Agreement".

• Construct underwater weir in the main Danube at Dunakiliti, (river kilometre (rkm) 1843, hereafter rkm) to increase the water level in the Danube, connect the Danube with the Hungarian river arms by openings in the river banks and regulate the supply of the Hungarian river branches with water up to 130 m³/s or even more.

• Collect and exchange environmental monitoring data, which is necessary for an analysis of the impact of the mentioned measures.

• Prepare National Annual Reports.

• Prepare Joint Annual Reports.

The results of the "Agreement" ensured the following surface water regime:

• The discharge into the Mosoni Danube increased, is regulated, and is permanently ensured all year round. Water is distributed into the Mosoni Danube arm, the Zatonyi Danube arm, and other Hungarian river branches.

• The Hungarian river branch system in the flood plain is permanently and sufficiently supplied with water. Water levels and discharges are regulated by the Dunakiliti weir and inside the Hungarian river branch system.

• The water level increased in the Danube riverbed, upstream from the submerged weir at Dunakiliti, as far as the Čunovo weir.

• These measures have also raised the ground water level.

Water management, proposed and accepted in the “Agreement” [1], is based on the principle that in the vegetation period discharges into the Old Danube and river Branches should be higher than in the winter period. Higher discharges in spring and summer, and changes in discharges, are typical, original, and natural in flood plain. Therefore natural discharges in Bratislava (at Devín) are taken as the basis for regulating discharges into the Danube downstream from Čunovo and into the Danube river branches. The system of river branches and canals supplied with water from the Čunovo reservoir and water impoundment upstream of the submerged (underwater) weir at Dunakiliti is shown in Fig. I.I and Fig. II.1.

To show the situation and the impact of measures immediately after constructing the submerged weir at Dunakiliti and implementing the water management measures, we quote from the first monitoring reports [2, 3].

After putting the Gabčíkovo part of the project into operation, a 20 m³s^-1 discharge was released by the Slovak Water Authorities at the Mosoni Danube intake into the seepage canal. From October 1994, in accordance with the agreement between the Slovak and Hungarian parties, this amount was increased to 40 m³s^-1. [2, 3]

From the 23^rd of June, 1995, the increased water level caused by the submerged weir at the Dunakiliti weir allowed discharging of 40 - 130 m³s^-1 of water into the branch system of the Hungarian flood-plain, directly from the Danube. The water level of the main channel of the flood plain was raised by 1 m on average. Thus, some side branches that had been totally dry (as a result of long term pre-dam development), could be, to some extent, supplied with water again [2, 3]. These main channel and side branches are now directly connected with the Danube by openings in the riverbank. The water level upstream of the submerged weir is on a level of about 123 m a.s.l. (meters above see level) and is regulated by the Dunakiliti weir.

Regular measurement of surface water quality had been carried out for many years before damming the Danube [2, 3, 4]. Long term monitoring of the Danube water shows improvement of the Danube water quality from the viewpoint of organic matter, plant nutrients, nitrogen and phosphorus [3].

The water quality alongside the Mosoni-Danube depends on a number of conditions. The most important factor is the water quality of the tributaries Lajta, Rábca and Rába [2], according to the Hungarian report. The quality of the Mosoni Danube water, mainly in the upper part, was substantially improved and resembles the Danube water quality. In the past, before building the intake structure into the Mosoni Danube, water stagnated in the upper part of the Mosoni Danube, and side river branches were without water or only with stagnant water. For most of the year the Mosoni Danube was disconnected from the flow in the Danube.

The area where there is a visible impact of measures realised according to the "Agreement" is defined as at least from the river branches lying closest to the Danube up to at least the Mosoni Danube river arm, and from Čunovo downstream to the Mosoni Danube estuary into the Danube at Vének village. In reality, impacts exist from the Danube to the area behind the Mosoni Danube. On the Slovak side, the impact of these measures is minimal, usually not measurable, and occurs only on the right side downward from Čunovo village and between the Danube and the reservoir from Čunovo to Dunakiliti. In general, the impact of measures realised according to the "Agreement" are visible in the whole Hungarian flood-plain and on the whole area of Szigetkőz.

References