Water levels at Kopački rit - endangered wetland

Na stanje vodnosti inundacijskog prostora oko Kopačkog rita ukazuju vodostaji obližnjih hidroloških postaja na Dravi i Dunavu. Samo stanje unutar Kopačkog rita, kao i na pojedinim postajama je međuzavisno sa svim okolnim stanjima. Procjenu ponašanja Rita omogućilo je relativno kratko mjerenje vodostaja samog Kopačkog jezera tijekom 2001. do 2003. godine. Iz analize istovremenih dnevnih vrijednosti vodostaja različitih lokacija konstatirano je poprilično rasipanje podataka oko prosječnih korelacijskih zavisnosti. Konstatiran je značajan utjecaj Dunava na vodostaje Rita i Drave. Dunavski uspor se javlja i uzvodno od Belišća. Uočljivo je da vodostaj na samom Kopačkom jezeru značajno ovisi o vodostaju kod Apatina, ali i trendu njegovog porasta ili opadanja. Od značaja je i prethodno stanje povećane vlažnosti ili sušnosti. Prema periodičnim podacima (stari 1949. - 1990. te novi 1992. - 2017.) potvrđeno je sniženje karakterističnih vodostaja u odnosu na prethodni period obrade te je konstatiran njihov daljnji trend sniženja. Prema podacima reprezentativne postaje Apatin proveden je proračun učestalosti i trajanja za nove podatke. Usporedbom izvedenih krivulja učestalosti i trajanja predmetnog vodostaja, za sukcesivne periode, utvrđeno je značajno smanjenje trajanja onih vodostaja koji osiguravaju ekološki presudnu vlažnost močvara Rita (kote 81,5 – 83,0 m n.m.).The status of water quantity in the inundation area around Kopački Rit is indicated by water levels at the nearby hydrological stations on the Drava and Danube Rivers. The status within Kopački Rit itself and the status at individual stations is interdependent. The assessment of the Kopački Rit behaviour was enabled by a relatively short measurement of water levels in Kopačko Jezero (lake) in the period 2001-2003. The analysis of simultaneous daily values of water levels at different locations showed a marked data dispersion in view of average correlation dependencies. It was concluded that the Danube River had a significant impact on the water levels in Kopački Rit and the Drava River. The Danube backwater occurs upstream of Belišće as well. It is noticeable that the water levels at Kopačko Jezero itself significantly depend on the water levels at Apatin, both with regard to its upward and downward trends. A preceding state of increased hu- midity or dryness is also of importance. According to the periodic data (1949-1990 and 1992-1997), a decrease in the characteristic water levels was confirmed in relation to the previous monitoring period, including a further downward trend. The data from the representative station Apatin was used in the calculation of frequency and duration for the new data. A comparison of the derived curves of water level frequency and duration for the successive periods showed a significant decrease in the duration of those water levels that ensure the ecologically critical humidity of the Kopački Rit wetland (81.5 - 83.0 m a.s.l.)