NUTRIENT EMISSIONS IN THE ZALA RIVER BASIN BUDAPEST UNIVERSITY OF TECHNOLOGY AND ECONOMICS DEPT. OF SANITARY & ENVIRONMENTAL ENGINEERING

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1 NUTRIENT EMISSIONS IN THE ZALA RIVER BASIN Adrienne Clement, Adam Kovacs, Istvan Sisak BUDAPEST UNIVERSITY OF TECHNOLOGY AND ECONOMICS DEPT. OF SANITARY & ENVIRONMENTAL ENGINEERING

2 Contents Characterization of the Zala River catchment Sources of nutrients (model results) Introduction of load reduction measures Impacts on water quality of Lake Balaton Conclusions

3 EUTROPHICATION OF LAKE BALATON I. II. III. IV. mg Chl-a m Basin IV Basin III Basin II Basin I Hypertrophic Eutrophic Mesotrophic Ologotrophic Before measures After load reduction

4 Specific P load (g/m 2 /a) Zala river basin Kis-Balaton reservoires River Zala is entering into the smallest, western bay of Lake Balaton, where enhanced nutrient load causes eutrophication.

5 AUSTRIA HUNGARY SLOVENIA Zala River catchment Lake Balaton A = 1528 km 2 Kis-Balaton reservoir Phosphorus load is measured daily at the outlet section of the Zala River. Zalaapati Zala River is located in the western part of Hungary, it t belongs to the watershed of Lake Balaton.

6 inhabitants are living in 100 settlements, the largest town t is Zalaegerszeg with more than half f of the catchment s s population. Zalaegerszeg III. IV. Zalabér I. II. Zalalövı Zalaapáti

7 Dominant land use activity is agriculture Grassland 8% Forest 34% Arable land 53% Other 1% Urban area 4%

8 Economic changes in 1989/90 resulted significant drop in fertilizer use. Now the nutrient surplus of the agricultural fields is about 10% compared with the mid eighties. 70 Phosphorus surplus [kg P/haAA] Sub-catchment I. Sub-catchment II. Sub-catchment III. Sub-catchment IV. Total catchment N surplus Nitrogen surplus [kg N/haAA] P surplus Sub-catchment I. Sub-catchment II. Sub-catchment III. Sub-catchment IV. Total catchment

9 Share of total P emissions from the Zala river basin within different sectors Wastewater discharge (direct) Agriculture Urban non-point Background (natural)

10 Share of nutrient emissions from the Zala catchment within different pathways (results of MONERIS model) 2,3% 7,2% 0,2% 6,6% Atm. deposition 5,0% Total emission: 123 t/a Overland flow Erosion Groundwater Phosphorus Urban systems 78,8% WWTP 22,1% 1,3% 5,9% 13,7% Atm. deposition Nitrogen 4,3% Total emission: 516 t/a Overland flow Erosion Groundwater Urban systems 52,7% WWTP

11 The main P sources related to erosion

12 Results of P load model PhosFate (Kovacs & Honti,, 2009)

13 P (erosion( erosion) sensitive areas BMP must focus on erosion protection and the control of fertilizer use

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16 In 1992 phosphorus precipitation was introduced at the largest wastewater treatment plant (Zalaegerszeg)) of the Zala catchment Now all of the collected wastewaters are treated biologically and chemically (additional( P removal)

17 Description of Small-Balaton Upper Reservoir Zala Lake Balaton Upper Reservoir Volume m 3, Mean depth 1.1 m, Retention time 1.5 month Watershed: 1550 km 2 Lower Reservoir

18 In 1985 the Upper Kis-Balaton reservoir was inundated in order to protect Lake Balaton against high nutrient loads carried by the river Zala. Total P retention in the reservoir is 20-50% (depending( on the inflow P concentration) Upper reservoir A = 18 km 2

19 Ingói cops (A=10 km 2 ) Lower reservoir (A=50 km 2 ) The Lower Kis-Balaton reservoir was partly inundated in Total P retention of the wetland (reedbed) area is low (10-30%) 30%), but...

20 ... But the entire Kis-Balaton area has significant ecological value (Ramsar area, protected habitat,etc etc.)

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26 KIS-BALATON: GLOBAL BEHAVIOUR Zalaapáti Fenékpuszta Alsó Tározó FENÉKPUSZTA (TP/YEAR) Before the operating of the Upper reservoir Upper reservoir with high external (sewage) load P precipitation in Zalaegerszeg, opening of the Ingói-crops (1993) Felsı Tározó ZALAAPÁTI (TP/YEAR)

27 KIS-BALATON: GLOBAL BEHAVIOUR TP (tonnes) Catchment of the lower Zala Direct catchment of the Ingói-cops Direct catchment of the Upper reservoir Zalaapáti inflow (Zala catchment upstream to Zalaapáti) 20 0 Zalaapáti Fenékpuszta Felsı Tározó Q=345 million m 3 /y Alsó Tározó Q=347 million m 3 /y Q=153 million m 3 /y 2001 Q=111 million m 3 /y 2002 Q=84 million m 3 /y Fenékpuszta outflow (load to Lake Balaton)

28 Common characteristics of P cycle of the Upper Reservoir External P load reduction due to control measures (5 2.5 g/m 2 /y) resulted in significant drop in P retention TP (t/y) IN (t/y) O UT (t/y) Reten tion (% ) Reten tion (% ) 70% 60% 50% 40% 30% 20% 10% 0 0%

29 KIS-BALATON: GLOBAL BEHAVIOUR Total Nitrogen 1200 tonnes Inflow Upper direct Lower direct Outflow N retention ~ 50% Suspended solids SS retention ~ 90% tonnes Inflow Upper direct Lower direct Outflow

30 Total P load from the Zala river basin has changed dramatically during the past 30 years. (data from river monitoring at the catchment outlet) Total P load (t/a) Construction of Kis-Balaton reservoirs Economic changes: drop in fertilizer use P removal at the WWTPs Drought

31 Relationship between P load and runoff 400 Total Ö P terh load elés (t/a) (t/év ) Surface Felszíni lefolyás runoff (éves (m 3 átlag, /s) m 3 /s)

32 Load reduction resulted in considerable improvement of water quality of the lake, particulary in the western bay. Total P (t/a) Chl-a mg/m Kis-Balaton P removal Agricultural collapse drought

33 Total P (tonnes/year) TP load of Lake basins before and after the introduction of load reduction measures agriculture wwtp s atmospheric urban runoff I II III IV natural background I II III IV

34 Summary & conclusions Success story: P load reduction resulted in significant water quality improvement Efficiency of measures Start with point sources! Increasing diffuse ratio Role of agriculture economic impacts or application of BMPs) Future load Further load reduction is necessary Climate impacts

35 TANHK YOU VERY MUCH FOR YOUR ATTENTION! BUDAPEST UNIVERSITY OF TECHNOLOGY AND ECONOMICS DEPT. OF SANITARY & ENVIRONMENTAL ENGINEERING