Water management problems in coastal karstic regions - interrelationship of natural processes and human impacts exemplified by Ra?a River estuary (Istria-Croatia)

摘要

Paper analyzes water management issues in coastal karstic areasrnexemplified in Ra?a River estuary (Istria, Croatia), characteristic for itsrndynamic natural processes inherent in the contact of surface watercoursesrnas well as numerous coastal springs with the sea. Human impact on naturalrnprocesses and water quality in the area is significant: extensive irrigationrnworks in a narrow zone of the Ra?a River estuary, carried out in thernbeginning of the 20th century, dried up shallow Krapanj Lake and part ofrncoastal sea in the estuary, forming Donja Ra?a amelioration system. Suchrnpractices caused significant changes in runoff regime of Ra?a River andrnseveral coastal springs in the vicinity (such as Fonte Gaia, Kokoti, Rakonekrnand Mutvica) that are part of water supply system. Influence of the sea onrnaquifer is evident in increased salinity and even long-term brackish springrnwater at several locations (springs Blaz and ?esuni). During 18th centuryrnand up until 1990, Ra?a River catchment area was considerably influencedrnby the coal mine that is now abandoned and the shafts sunken.