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Split, Croatia

The paper analzes characteristic water levels measured in the Vrana Lake on the Cres Island in the period from 1929 to 2013. The objective of the analyses carried out in this period was an attempt, by application of primarily hydrological methods, to determine the key factors which caused the concerning trend of decrease of water levels in the lake since 1982. The Vrana Lake is a very complex hydrological and hydrogeological system, which is also under strong anthropogenic influences due to water pumping from the lake for water supply of the islands Cres and Lošinj. Additonally, its functioning is impacted by climate changes/variations. This is mostly related to the impact of increase in air temperatures in the past two decades, since no trend of changed annual precipitation quantities was recorded. Due to the large surface of the water mirror, a slight increase in air temperature can cause significant increase of evapotranspiration from the water surface of the lake. Through analyses conducted in this paper, it was determined that increase in the mean annual air temperature of 1 °C causes annual increase in evapotranspiration from the free water surface of about 5.8×106 m3 of water, and increase of evapotranspiration from the land surface of the basin of about 1×106 m3 water. Source

Bonacd O.,Fakultet Gradevinarstva | Popovska C.,University of Macedonia | Gesovska V.,University of Macedonia
Hrvatske Vode | Year: 2014

Lake Dojran is located in the north-eastern part of the Balkan Peninsula. Its basin and water mass is shared by Macedonia and Greece. This valuable water storage in an otherwise hot, dry area is endangered by climate changes which, according to numerous experts, are consequential to global anthropogenic activities, but also local anthropogenic impacts, primarily uncontrolled, excessive use of lake water and surrounding groundwater for purposes of agricultural production. In the period from 1989 to 2002, a sudden decrease of the lake water levels occurred, by even up to 5 m, which caused deterioration of water quality, plankton reduction, decreased biodiversity, reduction of bird numbers, as well as numerous negative economic, social and political consequences. From 2003 to 2010, water levels rose by about 3 m. In the paper, an attempt was made to determine the reasons for such behaviour. For achievement of this objective, the only available data were data on precipitation, air temperatures and water levels measured on the Macedonian territory in the period from 1951 to 2010. Analyses showed that an important role in the lowering of water levels in the lake was played by increased air temperature, along with the impacts of anthropogenic activities. Source

Ostoiic-Skomrlj N.,Fakultet Gradevinarstva | Raduikovic M.,University of Zagreb
Gradjevinar | Year: 2012

The methodological procedure for forecasting cost distribution over time is given for the project realization phase using cost s-curves for three different types of structures: building, tunnel, and motorway. Three different approaches are used, and their results are correlated and presented in form of mathematical regression expressions and appropriate diagrams. The proposed methodology can be used for cash flow forecasting during all phases of construction projects, specially in the earliest phase in which detailed information about the project is scarce. Source

Bonacci E.O.,Fakultet Gradevinarstva | Fumet M.,University of Avignon | Sakic-Trogrlic R.,TU Dresden
Hrvatske Vode | Year: 2014

The paper carries out a complex water resource behaviour analysis of the Ombla karst spring. The Ombla is a typical coastal karst spring. It is located in the vicinity of the town Dubrovnik, and reliably supplies it with good quality drinking water. It appears on the surface at the attitude of 2.5 m asl, so its water almost immediately flows into the Adriatic Sea. Its minimum discharge is estimated at 4.30 m3s-1,and its maximum at 117 m 3 s-1. Considering the size of its recharge area and the abundant, intense precipitation which appears in it and also due to its karst character, it has been concluded that this is a spring with a limited maximum discharge capacity. With regard to its minimum discharges, it can be concluded that it is recharged from a stable, large karst aquifer. Its medium discharge in the natural state in the observation period from 1968 to 1980 equalled 28.01 m 3 s-1 From 1981 to 2012 (with the exception of the 1991-1992 period), i.e. in the period when the river bed of the Trebišnjica River, which flows through its catchment area, was regulated and turned into a concrete canal in the length of over 60 km, its medium discharge was reduced by 4.29 m 3 s-1 to the value of 23.71 m3 s-1 The paper presents the most recent hydrological analyses of water discharges and temperatures. A special attention was paid to the definition of the spring's catchment area. In the literature, this surface is estimated at about 600 km2, which is determined mostly through regional geological analyses. Due to a lack of reliable data, this paper could not determine the catchment area with certainty either, and even less reliably its boundaries. However, by application of a hydrological method, it was estimated that the catchment area is probably much larger, ranging between 850 km2 and 1100 km2. The behaviour of groundwater levels, measured in several deep piezometers drilled in its hinterland, was also analyzed. It was proven that the watershed between the Ombla spring catchment and the neighbouring catchment of the Zavrelje spring suddenly changes as a result of intense precipitation, and that waters from the aquifer of the Ombla spring occasionally spill over to the neighbouring springs. Source

Ljubenkov I.,WATER DEVELOPMENT d.o.o. | Vranjes M.,Fakultet Gradevinarstva
Hrvatske Vode | Year: 2013

For determination of hydraulic conditions in the Jadro river mouth, salinity and temperature measurements were carried out in the river bed in July 2012. These measurements confirmed that this was a "stratified" river mouth where fresh water flows above sea water in a thin surface layer. Additionally, a simulation of non-stationary stratified flow was carried out with a numerical model for certain hydrological states. The characteristic values of water level, flow and accompanying lengths of salt water intrusion in the river bed were determined, offering a good insight into the salinization processes in the Jadro river mouth. Source

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