Vízügyi Közlemények, 1999 (81. évfolyam)

3. füzet - Jolánkai G.-Bíró I.: földrajzi információs rendszeren alapuló integrált vízgyűjtő modell fejlesztés és alkalmazás a Zala-vízgyűjtőre

Földrajzi információs rendszeren alapuló integrált vizgyüjtőmodell 481 ing to the highest positive climate scenario (+7%). These were considered by driving the model with the respective modelled runoff map, for which an example was shown in Figure 4. Anthropogenic impacts and control strategies (scenarios) were considered as discussed briefly in Section 4. Since the combinations of these scenarios would result in a very high number, we have selected representative combinations thereof as shown in Table 7. below. This table also shows the numerical results of the simulation for the outflow station of the catchment at Zalaapáti. Results of the two extreme scenarios, the theoretically achievable best and the worst possible conditions (Scenario combinations 5. and 6.) are shown in Figures 8. and 9. in terms of the flow and phosphorus concentration profles of the River Zala. The main conclusion of practical value of the analysis was that excessive use of fertilizers will result in substantial enrichment of the nutrient content of the soil and in substantially increased instream loads. This conclusion was also supported by ample experimental evidence in this case study. This can be one more well supported argument in the ever lasting debate between agricultural experts and environmental experts on the effect of fertilizer usage (with special regard to phosphorus). Analysis of the potential effects of climate change scenarios with the reservoir simulation model. Running of the model was made with the 200 year long generated time series of the climate scenarios, a summary of which was presented in Table 2. As a comparison the model was also run with the flow records of the past decade in order to demonstrate the expectable changes. Results of the model run are summarized in Table 8. Summarizing, it can be stated that the negative climate scenarios (and especially PI ) would cause critical situation in the management of water resources in the Zala river basin. In an attempt to relieve the situation (to meet 90% duration low flow of the historic record at the river gauging stations) most of the reservoirs would be regularly emptied down to their minimum volume (10% of the total volume) in almost each year and there would be reservoirs that could not be filed at all. This means that in the case of actual climate change (when the region becomes drier) the water users of the Zala Basin will face quite serious water shortage, the duration of which, however, will be relatively low. The reality of this prediction was supported by running the model for the past decade (when the years 1993-94 were very dry, of drought character) and the operators of many of the reservoirs reported considerable water shortage. The authors consider the major result of their work the development of a GIS based catchment model system, which can actually be used in the practice for supporting water resources and water quality management decisions in the Zalá catchment, upstream of the Kis-Balaton reseivoir system. They also hope that the model system is suitable for adoption also in other catchments. This refers to the use of the cathcment model for the management of both point and non-point source pollution as well as to the use of the reservoir simulation model in setting the most appropriate operation rules for counteracting water shortages. * * * Entwicklung eines auf „GIS" basierende integrierten Einzugsgebietsmodells und seine Anwendung auf das Zala-Einzugsgebiet von Dipl.-Ing. Géza JOLÁNKAI, Doktor der UAW und Dipl,-Ing. István BIRÓ Das Ziel ist die Erstellung von zusammengesetzten Einzugsgebietsmodellen, welche geeignet sind, die quantitativen und qualitativen Veränderungen der Wasservorräte unter veränderlichen klimatischen, umweit- und wirtschaftlichen Bedingungen vorauszusagen und somit die die Abstimmung zwischen Vorräten und Bedürfnisse bezweckenden Maßnahmen vorzubereiten. Die Kalibrierung und Validierung der Modelle erfolgte aufgrund der Daten von englischen und ungarischen Mustereinzugsgebieten.