Vízügyi Közlemények, 1996 (78. évfolyam)

3. füzet - Hankó Z.-Starosolszky Ö.-Bakonyi P.: Megvalósíthatósági tanulmány a Duna környezetének és környékének fejlesztésére

314 Hankó Z.—Starosolszky Ó —Bakonyi P. tered drinking water resources and the supply of refreshing water to the river arms and induced the drying out of the islands of the region as well as that of the floodplain and the area outside the levees; — The level of the crest of flood levees is lower, along the middle and lower part of the river reach in concern, than what would be desirable for assuring flood safety; — Navigation is hindered on several parts of the river reach. The shallowest ford is 1.4 m deep and 80 m wide only; — As contrasted to this demans for both traditional and advanced cargo shipping via waterways will be likely increasing upon the effect of the opening of the Danube-Mine-Rhine canal and upon the expectable increase of east-west trading activities; — At the present the most important recreational resorts of the area include the vicinities of Esztergom and the Szigetköz. Resorts of the highesty recreational potential include Dunaalmás—Neszmély, Koppänymonostor and Vének. Combined development proposals for the rvier reach upostream of Budapest include: — Rahabilitation/revitalization of side river arms seems to be achievable, although at the expense of certain investments. This will improve the water quality, the ecological conditions and the touristic/recreation potential of the river arms; — Hydro-ecological developments of the river reach of Gönyű-Szap shall include the reducing of the degredation of the main channel bed. There is an eventual conflict between the interests of navigation and environmental protection. Resolving this issue needs further investigations, which shall include the Szigetköz area as well. — None of the single objective strategies (either environmental or navigational

) offer acceptable solution, while the Combined Strategy enables the environmental development (mostly via the development of river arms) along with the establishment of a waterway of the width of 80-120 m and of 2.0-2.7 m minimum draft. This Combined Strategy offers selection from among economically acceptable options, äs well. In the Danube reach downstream of Budapest the present conditions are characterized by the following peculiarities: — Industrial dredging, cutting of river bends and other river training works degraded the river channel along the Budapest—

Mohács reach. This creates hazards for both industrial and drinking water abstraction along the reach, including the water intakes of the Paks Atomic Power Plant; — River training works have improved the ice release capacity of river reach. Nevertheless there is still a substantial risk of the development of ice-jams in the river reach downstream of Paks; — The flushing rate of side river arms is low, since a substantial part of the side river arms is cut-off from the main channel, resulting in sedimentation and poor water quality. These conditions create hazards to natural resources, drinking water abstraction from bank-filtered resources, to recreation potential and also to fish management; — Industrial gravel dredging from the main channel and the works of river training limit the water abstration capacities form bank-filtered resources and deteriorate the quality of abstractable water; — Water level subsidence due to channel-bed erosion has contributed in the last decades to the problems of drying in both the floodplain and the protected area outside the levees. This is characterized by the decreasing timber output of forestry, too; — Navigation is hindered at several locations of the river reach. The shallowest ford is hardly deeper than 1.9 m; — Increasing demand for cargo shipping via waterways is expected in terms of both traditional and advanced means of water transport. This is mostly due to the opening of the Danube-MainRhine waterway system and to the expectable increase in eas-west trading activities. Combined development proposals for the Danube reach downstream of Budapest: — None of the alternatives investigated offer solution for the halting of channel bed degradation. Commercial dredging of gravel from the main channel must not be allowed since it results in serious consequences for the cooling water intakes and for the ecological conditions, as it results in drying processes;