The examination of the performances of methods used in separating the total stream flow in different rivers/Ispitivanje svojstava metoda koristenih za razdvajanje ukupnog vodnog protoka u razlicitim rijekama

In this study, the performances of methods of flow separation into the surface flow and base flow of the total stream flow in rivers with different hydraulic features have been examined. For this purpose, daily mean stream flow data of Buyuk Melen and Aksu Rivers which are in the same watershed but with different features (average flow value, catchment area, mean elevation) have been separated as surface flow and base flow with the use of Digital Filtering Method (DFM) and United Kingdom Institute of Hydrology Method (UKIH). The recession coefficient in DFM has been used as a = 0.830; and the number of elements for the groups formed to determine the turning points of flow data in UKIH has been used as N = 5. The study has revealed that the results of surface and base flows obtained by both flow separation methods show similarity in all rivers in an acceptable level; and the surface flow values agree better ([R.sup.2] > 0,76) compared to base flow values ([R.sup.2] > 0.63). However, it has been seen that as long as the total flow values decrease, the surface flow results for both methods come closer to each other; but the results of base flow get differentiated. This situation has been clearly seen in the results of surface ([R.sup.2] > 0.89) and base ([R.sup.2] > 0.63) flows belonging to Aksu River which has lower values of flow when compared to the ones of Buyuk Melen River. Keywords: separation of flow, surface flow, base flow, DFM, UKIH U ovom radu su ispitivana svojstva metoda razdvajanja protoka u povrsinski protok i pridneni protok ukupnog vodnog protoka u rijekama s razlicitim hidraulickim profilima. U tu svrhu, podaci srednjeg dnevnog vodnog protoka rijeka Buyuk Melen i Aksu, koje pripadaju istom slivu, ali s vrlo razlicitim odrednicama (prosjecni protok, povrsina sliva, srednja visina) radvojeni su na povrsinski protok i pridneni pritok koristenjem metode digitalnog filtriranja (DFM) i metode Instituta za hidrologiju Ujedinjenog Kraljevstva (UKIH). Za koeficijent recesije u DFM-u koristena je vrijednost a = 0.830. U UKIH metodi je koristeno 5 elementa (N = 5) za odredivanje tocke preokreta u protocima. U radu je pokazano da povrsinski i pridneni protoci dobiveni pomocu obje metode razdvajanja vodnog protoka pokazuju slicnost u svim rijekama na prihvatljivoj razini, te da se podaci povrsinskog protoka slazu bolje ([R.sup.2] > 0,76) od onih s pridnenim vrijednostima protoka ([R.sup.2] > 0.63). Medutim, vidljivo je da se, dokle god vrijednosti ukupno