Hydrogeological Conditions and the Necessity for Sanitary Protection of the Norinska River - Prud Spring, Metkovic, Croatia

Abstract

A detailed description of the hydrogeological relationships in karst aquifers from this part of the Dinarides, together with the recommended conditions for their protection are given. The Norinska river spring is recharged by groundwater flow from the northwest, mainly from the Jezerac polje region, the northern part of Rastok polje and the middle course of the Trebizat river. On the basis of geological, hydrogeological, hydrological and hydrogeochemical studies, it was determined that part of the water is lost to the subsurface in the region between the Ljubusko polje and the Kravice waterfall and is later discharged at the Norinska river spring. Due to the presence of sulphate, the chemical composition of waters from springs along the Trebizat river basin (and its headwaters), is similar to waters from the Norinska river spring. The sulphate in some springs along the north and north-east valley side of the Tihaljina river is the principal anion, and since these waters contribute to the waters in the Norinska river catchment they also affect its water chemistry. Turbidity and the occurrence of fine sand at the Norinska river spring confirms the existence of developed underground channels, conduits and siphons, along which groundwater flows at velocities greater than 5 cm/s during high pluvial periods. The origin of the sulphate is attributed to the presence of gypsum and anhydrite deposits in the deeper parts of the karstic aquifer. The groundwater protection zones were determined on the basis of the groundwater flow velocities, groundwater retention, urban development and the types of industries present within the areas covered by the Ljubuski and Vrgorac municipalities. Presented map is the basis for micro-zoning and the determination of locations for future mercantile (industrial) facilities. The study was focused towards surface karst phenomena and their protection from anthropogenic influence.