VERTICAL GROUNDWATER BALANCE OF THE DRAVA RIVER ALLUVIUM
Main researcher
: PATRČEVIĆ, VLADIMIR (35124) Assistants
VUKELIĆ, ZVONIMIR (139080)
MILKOVIĆ, JANJA (31636)
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
Communication
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
E-mail: patrcevic@public.srce.hr
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.
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.
COOPERATION - PROJECTS
Name of project
: 2-11-005 Solarni bazeni u uvjetima našeg
podneblja Name of institution: Građevinski fakultet Zagreb City: 10000 - Zagreb, Croatia
COOPERATION - INSTITUTIONS
Name of institution
: JVP "Hrvatska vodoprivreda" Type of institution: Institution whose primary activities ar City: 10000 - Zagreb, Croatia
Name of institution
: Komunalno poduzeće "Varkom" Type of institution: Non-profit City: 42000 - Varaždin, Croatia
Name of institution
: Državni hidrometeorološki zavod Hrvatske Type of institution: Institution whose primary activities ar City: 10000 - Zagreb, Croatia
Name of institution
: Građevinski fakultet Type of institution: Economical/Production City: 10000 - Zagreb, Croatia