engleski

Recession processes in Red Lake, Imotski

Red Lake near the town of Imotski in Croatia is one of the most impressive examples of karst features in the Dinaric Karst. This area is rich in karst formations, and Red Lake is one of the least explored. The reason for this is the difficult access to the lake, which requires more complex, demanding, and, above all, resource- intensive research. Therefore, the analysis of recession processes in the lake allows quantification of hydrological phenomena and insight into the hydrogeological functioning of the lake. The analysis is based on data on precipitation and water levels in the lake. Integral water inflow and outflow quantities were determined using the existing morphometric model of the lake, which defines the relationship between lake volume and depth. The average values of the recession coefficients, defining the dominant regime of the lake, were obtained from Master recession curves. The Master recession curve provides information on the average characteristics of the discharge components and was determined using 3 methods: Adapted Matching Strip Method, Tabulation Method, and Petraš Method. Since the object of study in this paper is a lake and not a watercourse, the strict definition of recession curves can not be applied. The recession periods of hourly water volume change of the lake were isolated, normalized and log transformed, therefore the analyzed periods are referred to as quasi-recession curves and the recession coefficients as quasi-recessions coefficients. Analysis of quasi-recession curves and calculated coefficients, define the relationship between the direct and baseflow component, further on they identify the predominant hydrogeologic mechanism as well as response of the lake to the precipitation and the lake's connection to a nearby spring. This approach can be used not only to identify the hydrogeological regime of karst lakes but also to stratify the different porosity levels of the surrounding karst massif.

Red Lake, recession curve, recession coefficient

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