Hydrologic Budget for the Poljes in Karst

Abstract

The poljes in karst have already been dealt with in Chapter 2 as a morphologic and surface phenomenon. As previously stressed, from the hydrologic standpoint, poljes represent a subsystem linked to the surrounding karst mass, other poljes or river valleys on higher horizons and to those poljes or river valleys on lower horizons. The preceding chapters discussed a few examples of the influence of the surface waters and groundwaters of higher and lower horizons under hydrologie conditions in the analyzed polje. When defining the water budget in the poljes difficulties arise in the flooding periods. In such situations it is very difficult, even impossible, to control the water inflow. Furthermore, the water then flows into the polje through a series of temporary springs and the estavelle function as springs. Figure 7.1 shows a probability curve for the dates of the occurrence of the maximum flood level in the Konavosko Polje near Dubrovnik (Yugoslavia). In addition to this curve, it is necessary to define the probability curves for the beginning and ending dates of the flood, as well as for the flood duration in the poljes. Flood analysis should be performed according to a schematic representation of the inflow and outflow hydrographs, i.e. according to the analysis of floods in the pre-ponor retention. Figure 7.2 A gives a graphic presentation of the inflow and outflow discharge hydrographs. It is the simplest case discussed by Ristić (1976). Figure 7.2B presents the water level hydrograph in polje H = f(t) and the curve of the water volume in the polje retention V = f(t), whereas Figure 7.2 C gives the mass curves of the inflow and outflow volumes.Probability curve for the data of occurrence of the maximum flood level in the Konavosko Polje (Yugoslavia)Analysis of inflow and outlow hydrographs in the flooded polje. A Inflow and outflow discharge hydrographs; B water level hydrograph in polje; C mass curves of the inflow and outflow volumesKeywordsWater BudgetProbability CurveTotal OutflowDischarge HydrographPreceding ChapterThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.