Vízügyi Közlemények, 1998 (80. évfolyam)
3. füzet - Gilyénné, Hofer A.-Nováky B.: Az éghajlati hatásvizsgálatok megalapozása a Zala-vízgyűjtő lefolyásának vizsgálatára
524 Gilyénné Hofer A.—Nováky В. Investigation of the impact of climate changes on the runoff from the Zala River catchment by Dr. Alice GIL YÉN-HOFER and Dr. Béla NOVÁKY, Civil Engineers Changes of the climate (and changes of land uses) have their impact on water management mainly through the resulting runoff changes. Consequently there is need for investigating the impact of climate changes on the runoff and for the development of models, which (among other) are suitable for exploring the long term expectable changes in the tasks of water management which are to cope with the changes of the climate (and thus the changes in land uses). The list and results of the most important Global Climate Models (GCM) are given in Table I. Regional effects of global climate changes can be assessed by the GCM models and thus the expectable changes in Hungary as well. (Table II.). All models predict temperature rises for Hungary upon the effect of global warming (Figure 1.) In the framework of the international EU supported project on the "Development of Integrated Catchment Models for Supporting water Management decision" the catchment of the River Zala (Figure 2.) has been selected for the Hungarian pilot zone and the model RHINEFLOW was chosen as the tool of analysis. Of the climate scenarios those included in Tables III. and IV. have been selected for precipitation and temperature changes, respectively, in investigating the climate impacts. The 3 selected scenarios for temperature and precipitation changes each, represent together 9 climate change scenarios. For the analysis of long term (historic) time series of observation data the precipitation and temperature monitoring stations shown in Figure 2 have been selected. In generating monthly precipitation time series 45 year records of 10 rain gauges have been utilized, while 34 year long records of monthly mean temperature data of 4 stations have been selected for the temperature analysis. Of the results of statistical analyses the empirical and fitted distribution functions of temperature and precipitation in June are shown on the basis of the records of Bak and Zalaegerszeg stations, respectively (Figure 3.). Gamma distribution function fitted best to rainfall data, while normal distribution characterized the temperature data. Climate time series were generated in three steps. First the areally weighted annual precipitation sum (P* a\i p) and mean annual air temperature (t' a ) Ai G) series were determined. In the next step the generated time series of annual precipitation sums and annual mean air temperature were split into monthly values. In the third step of the procedure the generated monthly precipitation records and monthly mean air temperatures were decomposed into those of the individual monitoring stations. Results of detailed statistical tests have verified that the use of this possibly most simple decomposition-generation method resulted in very good fits among the statistical parameters (expected value, Table V; standard deviation Table VI and correlations, Table VII.) of measured and generated records for all stations. The generated time series corresponding to climate scenarios consisted of 42 generated time series of 200 year length, e.g those of the three precipitation scenarios (P1-P3) and 10 stations and the three temperature scenarios (tj —of 4 stations. These are complementary to the also 200 year long generated temperature and precipitation series of the 10+4 stations corresponding to the present conditions. * * * Für verschiedene klimatische Szenaria generierte Niederschlags- und Temperatur-Datenreihen im Einzugsgebiet des Zala-Flusses von Dr.-lng. Alice GIL YÉN-HOFER und Dr.-lng. BÉLA NOVÁKY PhD Die Klimaänderung (sowie die Änderungen der Landnutzung) wirken sich auf die Aufgaben der Wasserwirtschaft hauptsächlich über die Veränderungen des Abflusses aus. So ist es nötig, einerseits die auf den Abfluß ausgeübten Auswirkungen einer möglichen Klimaänderung zu untersuchen,
