Regional Analysis of Tracer Tests in the Karstic Basin of the Gacka River (Croatian Dinaric Karst)

Tracer testing is the only method in karst hydrogeology that can definitively determine whether a particular site belongs to watershed of spring. Therefore, it an essential technique for delineating groundwater basins areas. The availability tracer test results often limited due complicated and relatively expensive application this approach, especially large regional watersheds. Croatian part Dinaric region extends several hundred kilometers along Adriatic coast consists almost entirely highly karstified carbonate rocks. these areas never match surface morphology terrain. In practice, all available previous surveys are used define watersheds, regardless methodology age their implementation. This also true earlier delineations Gacka River watershed, basin karst. However, methods, accuracy determination monitoring, have improved significantly during time. order assess reliability past tracing significant basin, we reviewed reports tests. More recent tests, most multitracer injection with continuous detection on major springs, produced high-quality data allowed us findings from prior research. A number springs partially overlapping subcatchments feed River. After discarding unreliable data, reevaluated main as well characteristics flow patterns throughout which particularly important water quality protection measures springs. case study emphasize importance thoroughly assessing before using them analyses.