Naslov
Seasonal temperature variations of Lake Vrana on the island of Cres and possible influence of global climate changes

Autori
Kuhta, Mladen ; Brkić, Željka

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Izvornik
Congress Program and Abstracts / - Niagara Falls : International Association of Hydrogeologists - Canadian National Chapter, 2012, 280-281

Skup
39th International Association of Hydrogeologists Congress

Mjesto i datum
Niagara Falls, Kanada, 16.09.2012. - 21.09.2012

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Vrana Lake; Cres; karst; climate changes; water temperature

Sažetak
Lake Vrana on the island of Cres in the Croatian part of the Adriatic Sea is one of the largest fresh water features on Mediterranean islands. The maximum depth of the lake is 72 m (60 m below the sea level) and it stores 220 million m3 of fresh water. Due to exceptionally good water quality the lake is used to supply water to the islands of Cres and Lošinj and it is the only source of potable water for these islands with their highly developed tourism. The paper provides an overview of lake temperature and level measurements to date and recent activities within the EU project “Climate Change and Impacts on Water Supply” (CC-WaterS, SEE-TCP). Groundwater temperatures in lake surrounding are almost constant throughout the year, mildly dropping according to the depth, in the range from 14.6 to 13.1 °C. The temperature of the lake water changes throughout the year, and thermal stratification occurs at the end of summer. In the water layer above the thermocline, water temperature can reach up to 25 °C or more. At the same time, water temperature is very low in the hypolimnetic area and, depending on annual climate characteristics, ranges from 6.5 to 9.3 °C. In the isothermal period, which lasts from 2 to 3 months, the whole water mass has a homogenous temperature within 4.65 to 8.9 °C recorded range. Earlier collected data of lake water temperatures are rare and insufficient for analyses of a potential impact of climate changes. Results of long-term lake level observations (1929-2011) reveal significant trend of mean annual water level decline, nevertheless there is no trend in annual precipitation rates. According to the data from the period 1951-2009 an increase in the mean annual air temperature of 0.1 °C per decade is present since 1951 and it is amplified within the recent shorter periods (up to 0.4 °C/10 yrs in period 1981-2009). Present and future climate simulations using three limited area models were analyzed (Aladin, Promes and RegCM3), and they pointed out further temperature increase in range of 0.27 to 0.32 °C/10 yrs. The significant changes of precipitation rates were not indicated. Considering increasing water consumption and indicated climate changes in synergy with lake volume reduction, water temperature increase and biological changes, the further progressive lake level drawdown and water quality deterioration may be expected.

Izvorni jezik
Engleski

Znanstvena područja
Rudarstvo, nafta i geološko inženjerstvo

Napomena
Cjeloviti rad objavljen je u Zborniku radova na USB memorijskom disku pod brojem 142

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