AUTOCORRELATION AND CROSS-CORRELATION FLOW ANALYSIS ALONG THE CONFLUENCE OF THE KUPA AND SAVA RIVERS

Abstract

In this paper, an autocorrelation and cross-correlation analysis of the flow of the Kupa and Sava rivers was performed. The analysis was performed at hydrological stations close to the confluence of these two rivers near the city of Sisak, based on data of mean daily flows and daily precipitation. The analysed time period is from 2008 to 2017, with the series being divided into two parts of five years each, from 2008 to 2012 and 2013 to 2017. Daily flow data were measured at the hydrological stations Farkašić on the Kupa River and Crnac on the Sava River, and data on precipitation at the main meteorological station and the automatic meteorological station Sisak. The maximum value of the cross-correlation function between the hydrological stations at the Kupa and Sava rivers is very high, but at a time lag of zero days. The value of the cross-correlation function remains high, up to 0.6 and up to a 4 day lag. The cross-correlation function between precipitation and hydrological data has a very low maximum value.

Alternate abstract:

U ovome radu provedena je autokorelacijska i kroskorelacijska analiza toka rijeka Kupe i Save na hidrološkim postajama u blizini ušća Kupe i Save nedaleko od grada Siska, na temelju podataka o srednjim dnevnim protocima i dnevnim količinama oborina. Analizirano je vremensko razdoblje od 2008. do 2017. godine, s tim da su vremenski nizovi podijeljeni u dva dijela po pet godina, od 2008. do 2012. i od 2013. do 2017. Podatci dnevnoga protoka mjereni su na hidrološkim postajama Farkašić na rijeci Kupi i Crnac na rijeci Savi te su uzeti podatci o oborinama na glavnoj meteorološkoj postaji i automatskoj meteorološkoj postaji Sisak. Maksimalna vrijednost kroskorelacijske funkcije između hidroloških postaja na Kupi i Savi vrlo je visoka, ali u vremenskome kašnjenju od nula dana. Vrijednost kroskorelacijske funkcije ostaje visoka do 0,6 i do 4 dana zakašnjenja. Kroskorelacijska funkcija između oborina i hidroloških podataka ima vrlo nisku maksimalnu vrijednost.