SVIBOR - Project code: 2-11-006


Strossmayerov trg 4, HR - 10000 ZAGREB
tel.: +385 1 459 44 44, fax: +385 1 459 44 69


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Project code: 2-11-006


Main researcher: PATRČEVIĆ, VLADIMIR (35124)

Type of research: applied
Duration from: 01/01/91. to 12/31/97.

Papers on project (total): 3
Institution name: Građevinski fakultet, Osijek (149)
Department/Institute: department of hydrotechnic
Address: Drinska 16a
City: 31000 - Osijek, Croatia
Phone: 385 (0)1 33-68-11
Phone: 385 (0)31 44-377
Fax: 385 (0)31 24-348
Fax: 385 (0)1 33-68-11

Summary: It is known that through the aeration zone of the soil there is a constant exchange of water between the free of groundwater and the atmosphere. This exchange manifests itself through three basic hydrological processes:PRECIPITATION (rain, snow, dew), INFILTRATION (effective infiltration), EVAPORATION (evapotranspiration, evaporation of ground water). All three processes are of fundamental importance for the feeding of ground waters. It is therefore essential for a good utilization of ground waters that we are well acquainted with the physics of these processes, with their volume in certain time-intervals, as well as with their comparative relations in different part of the year.Groundwater losses are the result of evaporation (evapotranspiration) and the ground water is renewed through effective infiltration of the precipitate in a certain area. As a rule, evapotranspiration and infiltration are the main factors of the hydrological water balance of an area. For the total water balance of a time-span such as a whole season, a month or an even shorter period, these vertical groundwater-balance factors are far more important as feeding elements of the ground waters than the horizontal factors. The only exception to this is a narrow area close to waterflow which is dominantly influenced by the surface inflow and river-water. The analysis of the interaction of the vertical components in the processes of the flowing of the water through a porous ground - a section between the atmosphere and the groundwater level has shown that the losses of the water due to actual evapotranspiration take a specially importan place among all other hydrological processes. In order to determine the losses, practitians often use different approaches without any objective criteria. They most often apply empirical methods with coefficients set for some other, different climatic and geological areas, or they use evaporation data obtained on different evaporators in meteorological station. As a rule, such approaches to hydrological calculations always require the input of the factor of incertainty and signifficant errors. The rational theory of groundwater evaporation, as well as the infiltration to its free level is comprised in the laws of water and air movement in an unsaturated porous environment. A most thorough understanding of hydrological processes and of the natural laws of the flow of the water from the underground into atmosphere and the other way around is possible on through direct measuring in special measuring stations equipped with a lysimeter and an infiltrometer with the required meteorological equipment as it is the case with the experimental station "Varkom" in Varaždin.

Keywords: Precipitation, infiltration, evapotranspiration, ground water, water balance, infiltrometer, experimental station, piezometer.

Research goals: The aim of the research in this project is to determine the laws of the change in the water-regime of the groundwater through long-term measuring on the experimental station "Varkom" in Varaždin and within the specific charasteristics of the micro-climate and the hydrological situation in north-western Croatia. With respect to the wide hinterland or the river Drava alluvium, where vertical factors in the water balance of the groundwater appear as dominant, different lines of the research are directed towards the determination of the regularity of the change in these items (effective infiltration, moisure level of the soil, evapotranpiration) in the function of the depth of the groundwater and in the meteorological parameters (air humidity, precipitation, air temperature, air-pressure, wind, etc.) All these measurings are being acquired on the experimental station "Varkom" and the ordinary meteorological station OMS Varaždin. The researcs done so far das given as a result quantitative data of the daily, monthly, seasonly and yearly amounts of effective infiltration and respective coefficients of infiltration and it has also shown the losses due to evaporation from the groundwater level, as well as total losses in terms or actual evapotransporation under different working conditions to the depht of 2m in the groundwater. The effective porosity of the hydrogeological environment as a very important parameter in the balancing of the groundwaters has also been determined through measuring. Since feeding quantity of the groundwater is a result of effective infiltration down to theirlevel, i.e. the difference between precipitation and total evaporation, it is especially importtant to determine the real actual evapotranspiration. The evapotranspiration is in our conditions basically calculated through certain empirical methods from the literature with coefficients which have not been checked for our climate. Therefore, a very important result of the research carried out so far on the experimental station is the creation of an original method for the determination of actual evapotranpiration, based on the hydrological and energetical balance, and applicable to the climatic and hydrogeological characteristics of a wider area of the river Drava alluvium. The essentials of this new method have been presented in the Miscellany of the Internetional Congress on Evaporation and Evapotranspiration organized by the WMO in 1993.


  1. Name of project: 2-11-005 Solarni bazeni u uvjetima našeg podneblja
    Name of institution: Građevinski fakultet Zagreb
    City: 10000 - Zagreb, Croatia


  1. Name of institution: JVP "Hrvatska vodoprivreda"
    Type of institution: Institution whose primary activities ar
    City: 10000 - Zagreb, Croatia

  2. Name of institution: Komunalno poduzeće "Varkom"
    Type of institution: Non-profit
    City: 42000 - Varaždin, Croatia

  3. Name of institution: Državni hidrometeorološki zavod Hrvatske
    Type of institution: Institution whose primary activities ar
    City: 10000 - Zagreb, Croatia

  4. Name of institution: Građevinski fakultet
    Type of institution: Economical/Production
    City: 10000 - Zagreb, Croatia

  5. Name of institution: Institut građevinarstva Hrvatske
    Type of institution: University/Faculty
    City: 10000 - Zagreb, Croatia

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Last update: 10/04/95