Exceeding Turbidity versus Karst Spring Discharge during Single Rainfall Events: The Case of the Jadro Spring

Abstract

The relationship between karst spring discharge and turbidity during periods where the turbidity exceeds the permitted value of 4 NTU is analyzed by means of classical hydrological methods including hysteresis loops. The Williams method (1989) is adjusted by replacing river discharge with karst spring discharge, and sediment concentration with exceeding turbidity. The study’s first part focuses on the general hydrological characteristics of cumulative rainfall, turbidity, and discharge during each period. In the second part, four major types of hysteresis loops are identified, classified, and hydrologically explained. The study area is the karst catchment of the Jadro Spring in Croatia. The obtained results show that hysteresis loops can be very useful in analyses of water turbidity from karst springs. A relationship between the type of loop, intensity of discharge, and size of the secondary peak in turbidity is identified. The major types of hysteresis loops were clockwise, counterclockwise, figure-eight and complex loops, and their main characteristics were summarized. The results gave a new insight into the behavior of the turbidity of the Jadro Spring.