Fertő Tó/Neusiedler

Fert ı tó/Neusiedler See

Miklós Pannonhalmi Deputy director North-transdanubian District Environment and Water Directorate Gy ır/Hungary Location of the lake transboundary lake shared by Austria and Hungary

Lake • Last and most western soda lake in Europe • One of the most turbid and opaque inland water • Astatic type, only 9 days/y windstill • Low degree of transmission, light/P limitation • Larges closed Phragmintes monoculture in Central Europe. • More soft mud than water in the lake basin • Trophic situation: meso-eutprophic • UESCO Biosphere Reserve • European Biogenetic Reserve • IUCN National Park • World Natural Heritage The mysterious lake 1318. Partly dried out instead of lake a river. 1410. High water level population escape to East, Apetlon was established 1568. Low water level period, Earl Nádasdy widow diverted the Répce river. Order to rehabilitation by the chamber. 1674. Lake width aprox. 3830 m. by Ruszt notice in Seehof 1693.-1736. Water surface slowly disappear against high precipitation. 1740. Lake dried out. Agricultural activity was planned. 1768.-1769. Water level begin to rise. 1786-os Lake surface > 500 km2. Several thousends of acres under water . Farmers escaped. 1801-tıl Water level begin to drop. 1811 Completly dried out. 1838. March. Flood events 356 km2 surface level. 1865. By Apetlon and Eszerháza narrow water surface, lake bottom dried out. 1872.-1880 High water level again, 2-3 m. water depth. 1902. Low water level. Commission was delegated by the Ministry of Agriculture. (Sontagh commission)Chemical and physical investigations. Fert ı/Neusiedler See 1781 After 130 years Kidny-shaped body extending approximately

from 47 0 38' to 47 0 57' N and from 16 0 41' to 16 0 52' E

Lake surface at 116.00 m.a.s.l. Catchment area: 1120 km2 315 km 2 Austria: 240 km 2 Hungary: 75 km 2 Reed surface:180 km 2 Austria: 117 km 2 Hungary: 63 km 2 Hungary‘s lake surface covered 85% by reed 1 cm level change 3 km 2 surface change Water management cooperation between H-A Cross border tradition Back to the 16th. century 1873 Rába River Regulation Association 1955 Austria neutral state 1956 Hungarian-Austrian Water Commission

Since 2000 based on River Austria Hungary Basins and Common implementation of the EU Water Framework Directive Common lake management Hungarian-Austrian Water Commission est. 1956 Common water mamagenet principles

Winter period priority has the lake. Max. capacity of the system 15 m3/s.

Summer period priority inland water.

The max. water level: 116,0 m.a.s.l.

Regulation levels

Winter period October – February 115,70 m.a.s.l. Summer period April – August 115,80 m.a.s.l. Sodium type lake

2004/05 K

CO3 Na

HCO3 Ca

Cl Mg

SO4 Chlorophyll-a

Chlorophyll-a

45 Mezo-eu 40

35 MIN

g/l 30 MAX µ AVER. 25

15 Mezo 10 5 Oligo 0

0 3 6 3 6 97 97 97 00 00 1 1 1 1979 1982 1985 1988 1991 1994 1997 2000 2 2 WFD

Lowland soda type 1-3 m depth – stabile - big

Environmental objective Good ecological status Reed belt development 1872 – 2007(during 135 years)

1872 1901 1957

1967 1987 2007 Sewage treatment Point sources Wulka river retention pond diffuse pollutions Rákos brook wetland Diffuse loads Indications of eutrophication General reed belt nutrient turover 3- H2S CH 4 CO 2 PO 4 N2 CO 2

Dissolved Oxigen sulf./methane bact. Organic N - -- NO 3 SO 4 Inorganic NH 4-N

O2 O2

Organic material C 250 mV below 100 mV Aerob Anoxic Anaerob S2- 200 – 100 mV

Organic P

Inorganic PO -P FePO 4 4 Fe III . Fe II.

Fe III. FeS Oxygen conditions May – September 2008. Hungarian part Climat change some Conclusions (A)

• Lake Neusiedl very sensitive to climate change. • A warming of 2.5 K leads to an evaporation increase of more than 20 %. • To compensate the evaporation losses and precipitation increase of + 20 % is needed, which is not very likely looking on state of the art regional scenarios. • Critical lake levels for tourism as 150.0 m.a.s.l. will change there return period from some 250 years in the past to less then 10 years within the next decades. • Adaptation seems to be possible but may be expensive and include some possible negative biological reactions in the lake. Adaptation strategies Only possibility to stabilize the lake level is to bring in water Endowment: tree options are discussed: Lajta river water

Water from the ground water table (Bankfiltration) of the Danube.

Water from the river Raab from the Hungarian side. Adaptation strategies • The mixing of the salty lake water with the Danube water may cause a clearing of the water, leading to massive growth of water plants. • Large additional water inflow may decrease the salinity and accelerate the growth of reed. Resolution of the Hungarian- Austrian Water Commission Climat change Short term: no need of endowment from the ecological point of wiev Long term: climate change and a hazard of disapperarance of the lake as a landscape, endowment needed. When?

Fert ı tó historical water levels 1600 - 2007

kiöntés 2 1786 1838 1941 1996

1625 1674 1690 1770 1854 18721880 1929 magas1

közep 2007 0 es 1801 Vízállás alacson y-1 1610 1768 1902 1992 kiszára 1740 1811 1813 1865 1870 1964 dás-2 1600 1650 1700 1750 1800 1850 1900 1950 2000 Objectives

1. Decrease reed belt growth. 2. Reduce point like loads. 3. Minimize diffuse loads. 4. Reduce internal-loads. 5. Sustainable reed management 6. Common H-A lake strategy Thank you for your attention