engleski

Improvement of Water Supply on Inhabited Croatian Islands

Croatia is a country with 1, 185 islands, reefs and rocks, of which only 47 are inhabited regularly and 15 periodically. Despite of their small area - 3, 300 square kilometres - i.e. approx 5.3 per cent of Croatia territory, they are of crucial importance for Croatia due to depopulation trend and their tourist attraction. Unfortunately, one of the most limiting factors in their development is the undeveloped water supply system. The goal of this study was to scan prevalent conditions and to propose optimal solutions for water supply on the islands. Having made rounds of all inhabited islands it was observed that there was a certain quantity of available fresh and brackish water on most islands, but of inadequately explored quantity and quality. While availability, demand and distribution of water on each island are determined by their specific conditions, there are a number of attributes common to the all Croatian islands: dependence of water demand on the season, lower in winter, higher in summer, and between the users, low for locals-high for visitors, small and widespread communities as well as water utilities with limited funding and know-how capacities. The bigger islands have quite satisfying water supply on which the population density and habitation pattern influence the extent to which consumers are supplied by piping networks, or to which they rely on their own sources of drinking water. The islands at a larger distance from the inland are usually supplied by water transport from the inland or with water from their own tanks, boreholes or wells, whose quality is often not satisfying. Water analyses of the samples taken showed the amount of totally dissolved solids from 300 up to >2000 mg/L, salinity from 0 to 8.1 and TOC from 0.29 to 14.48 mg/L. Brackish water presents huge potential for water supply due to the possibility of direct connecting to the water distribution system after the membrane process treatments. All islands were divided into four groups, i.e. the islands which: 1. have solved water supply ; 2. will solve water supply by water input from the inland in the near future ; 3. have not solved water supply entirely and 4. have not solve water supply at all. This study is dealing with the last two groups. In regard to the suggestions for solving of water supply on the Croatian islands which have not solved the water supply entirely and which have not solved the water supply at all, it can be stated that the water input from the inland is the right solution for bigger islands and those closer to the inland. Rain harvesting and its retention in the underground or on the surface is very acceptable solution for islands, where if necessary their own tanks could be filled by a water carrier or by a permanent mobile desalination plants during summer. Combination of desalination of huge amounts of brackish water and depositing of that water in the already existing reservoirs could solve the problem especially for the islands at a large distance from the inland. The existing resources of fresh and brackish water must be protected and additional hydrogeological research of quantity and yields must be carried out. Special attention must be paid to the waste management, since most of the islands do not treat domestic effluents, which are then discharged into the sea.

Croatia; islands; water supply; fresh and brackish water; rain harvesting; water quality; water demand

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