WATER AND LANDSCAPE MANAGEMENT ASPECTS IN THE LAKE NEUSIEDL REGION

Loiskandl W., Kogelbauer I., Nolz R., Grabenhofer H.
Universität für Bodenkultur Wien, Institut für Hydraulik und landeskulturelle Wasserwirtschaft
Nationalpark Neusiedler See - Seewinkel 

Abstract

The “Neusiedler See-Seewinkel” is the first and biggest Ramsar Site in Austria designated in 1982. In 2009 a transboundary Austrian-Hungarian site “Neusiedler See-Seewinkel-Hanság” was inscribed to the List of Wetlands of International Importance including present Ramsar Sites in both countries. Aside from that, a national park “Neusiedler See-Seewinkel” was founded in 1993 and co-managed with the Hungarian national park “Fertő-Hanság”, founded in 1991.
These sites consist of the lake Neusiedl itself, small salt lakes, salt meadows and fens. The lake Neusiedl is a steppe lake with an extensive reed area and marshes. It is one of the biggest wetlands in Central Europe covering a total area of 321 km², whereof the free water surface covers 143 km² and the reed belt covers 178 km² (Csaplovics, 1997). The water balance of the lake is dominated by precipitation and evaporation and just minor inflow of the river Wulka. Originally, the lake has no natural outflow, but at the end of the 19th century an artificial channel for access water drainage was constructed. Nowadays the lake water level is regulated by a weir according to operation rules and supervised by an Austro-Hungarian committee for water bodies. The operation rules define a water level range, however the lower limit is prone to draught conditions. For this reason, an important aspect of the water management actions, like building of small weirs or closing of channels, is the water retention in the area.
For improvement of lake water management a cooperation project “New Geodetic Survey of the Lake Neusiedl–Hanság-Channel System” between Hungary and Austria was initialised in order to provide a homogeneous topographic data base of the Lake Neusiedl basin and the Hanság-Channel including the investigation of the huge, stratified mud body of the lake and the reed bed. For the detection of the sludge layer and the lake bed echo sounding techniques of spatial and vertical high resolution were used for the free water surface. Single-point measurements were conducted as a reference with a new adapted measuring technique. They provide a high-resolution vertical profile of the sludge distribution and the bottom layer. Further single-point measurements were conducted in shallow water areas below 60 cm, where the use of echo sounding is limited, as well as in the hardly accessible reed belt.
The acquired knowledge about the state of the lake is essential for an appropriate lake and wetland management and overall landscape preservation.

Keywords: shallow lake, transboundary cooperation, water management, water level regulation, lake survey