CLIMATE CHANGES – SOME OBSERVATIONS IN CROATIA
Marija Beraković, B.Sc.
Boris Beraković, D.Sc.Prof.
Ksenija Cesarec, M.Sc.
Co-author
B.Magovca 161.
Faculty of Civil Engineering
Meteorological and Hydrological
10010 Zagreb, Croatia
University of Zagreb
Service of Croatia
Kačićeva 26,10000 Zagreb,Croatia Grič 3,10000 Zagreb, Croatia
marija.berakovic@zg.t-com.hr boris.berakovic@grad.hr
cesarec@cirus.dhz.hr
Keywords: precipitation, surface water, temperature, changes, water resources management
ABSTRACT
This paper presents some measurements of climatic elements (temperature, precipitation) and surface
water in Croatia, which indicate, like in the rest of the world, significant changes in last twenty years.
Recognized changes in climate elements and regime of the surface water indicate consequences on
water resources management and necessity for investigation of the causes, which affected the changes,
and appropriate planning and realization of meteorological and hydrological measurements (quality of
measurements (distribution, period, instruments) and quality of interpretation).
FOREWORD
Analysing climatic elements on the Drava river basin, the Lika area and Primorje show that the
climatic patterns formed on the present meteorological observations are going through some changes.
The results of conducted researches show what these changes are and in when they occur.
This paper shows the results of researches main climatic elements, precipitation and air temperature,
which have the dominant role in climate formation and water patterns of certain areas. Also shown are
the discharges which are influenced by the change in temperature and precipitation patterns.
CHARACTERISTICS OF ANALISED AREAS
The Drava river area (Figure 1) in Croatia with its 7440 km2 includes the area of Pannonian Basin and
several mountainous areas with a number of larger and smaller streams flowing into the Drava river.
In this area, the average mountain altitudes range from 100 to 800 m above sea level.
Lika mostly comprises of mountainous areas (Figure 2). The highest mountain peaks range between
1500 and 1700 m above sea level. Within these mountain ranges, many karst plateaus are located at
relatively high altitudes, ranging from 450 to 700 m above sea level. Streams rich with water run
through and sink into these plateaus. Major rivers are Lika and Gacka, considered among the longest
underground streams in the world.
Figure 1 Drava River Basin
Figure 2 Lika and Primorje area
The observed area has Mediterranean, continental and mountain climate with transitional areas
between these climate types.
The average yearly precipitation of the Drava river area ranges from 700 mm to 1200 mm. In
Primorje, it ranges from 1300 mm to 1400 mm. In the Lika area, including its mountain regions, the
average yearly precipitation ranges from 1200 mm to 3500 mm.
The average yearly temperature of the Drava river area ranges from 10°C to 11°C. In the Primorje
area, this is 14, 7°C (Senj) and inland it is 8, 7°C (Gospić).
THE CHANGE IN THE PRECIPITATION PATERNS
The Drava River (Figure 1) For climate stations Durdevac, Slatina and Donji Miholjac yearly course
for two characteristic periods from 1961 to 1990 and from 1991 to 2003 was observed as shown on
Figure 3. In the period from 1961-1990 precipitation maximum was mainly observed in June, which
was considered as one of the main characteristics of the continental precipitation pattern. After 1990
the heaviest precipitations appear in September. This change in September especially comes into
significance because September, alongside February and October, was before the change among the
driest months in this area. The difference in average precipitation for the month of September in the
two observed periods ranges for particular rain gauge stations from 71% even to 93%. This is the
increase of average precipitation in September for the 1991-2003 period.
The change in the precipitation patterns affects the change of the water patterns, which can be partially
seen on the Figure 4, which shows the yearly discharge course for three rivers.
The Lika and Primorje area (Figure 2) In this area stronger or weaker Mediterranean climatic
influence prevails and its characteristic is that the most of the yearly precipitation is in the cold part of
the year (around 60%). Figure 5 shows a yearly course of precipitation for two characteristic periods
from 1961-1990 and 1991-2005. There are no major differences in average yearly precipitations for
these two periods. The difference is in the redistribution of precipitation within a year. The influence
of the precipitation change on the river discharges can be seen on Figure 6.
TEMPERATURE CHANGES
Natural fluctuations in temperature in the last two decades have been disturbed by the excessive
pollution of atmosphere, so now they include exceptionally unfavourable and uncertain trend of
temperature increase.
The Drava River The air temperature in the Drava river basin was observed from the climate station
Durdevac and Donji Miholjac for the period of 1961-2003.
The change in temperature over time is noticeable on the diagram of the mean yearly temperature for
Durdevac on the Figure 6 and for Donji Miholjac on the Figure 7. These changes are occurred since
1987. The average yearly air temperature on the climate station Durdevac has increased by 1,16 °C in
the 1988-2003 period with regard to the 1966-1987 period, and on the climate station Donji Miholjac
it increased by 0,87 °C.
VOĆINKA - Mikleuš
Donji Miholjac
100
61/90
90
Qaverage (m3/s)
91/03
80
P ( mm )
5
5
4
4
3
3
2
2
1
1
0
70
60
50
40
30
I
II
III IV
V
VI VII VIII IX
X
XI XII
61/90
91/02
I
II
III IV
X
XI XII
X
XI XII
1,2
100
61/90
90
91/03
61/90
1,0
Qaverage (m3/s)
P ( mm )
VI VII VIII IX
KRAJINA - Čačinci
Slatina
110
80
70
60
50
91/02
0,8
0,6
0,4
0,2
40
0,0
30
I
II
III IV
V
VI VII VIII IX
X
I
XI XII
II
III IV
V
VI VII VIII IX
VOJLOVICA - Čačinci
Đurđevac
4,0
120
110
100
90
80
70
60
50
40
30
61/90
Qaverage (m /s)
P ( mm )
V
3
91/03
3,5
61/90
3,0
91/02
2,5
2,0
1,5
1,0
0,5
I
II
III IV
V
VI VII VIII IX
Figure 3 Rainfall – monthly variations
X
XI XII
I
II
III IV V VI VII VIII IX X XI XII
Figure 4 Hydrograph – Drava river area
The Lika and Primorje area In the Lika and Primorje area air temperatures from meteorological
stations Senj, Gospic and Licko Lesce have been observed for the 1961-2005 period.
The mean yearly temperature reached in 45 year the highest value on all stations in the year 2000. The
maximum monthly mean temperatures, for these stations were in the last 45 years the highest in May,
June and August of 2003. The majority of absolute maximum monthly temperatures were registered in
the last two decades. However, a few absolute minimums were registered in that period. With an aim
of pointing out changes in temperature over the last years, mean yearly temperatures for Senj are
shown in Figure 8 and for Gospic in Figure 9. The figures of mean yearly temperatures and conducted
tests have affirmed that the increase of mean yearly temperatures has appeared at the end of the
eighties. The increase of average yearly air temperature for Senj between the 1961-1987 and 19882005 periods amounts to 0,8 °C, and 0,9 °C for Gospic.
NOVČICA - Lički Novi
Senj
6
200
180
Qaverage (m3/s)
160
91/05
140
P ( mm )
70/90
5
61/90
120
100
80
91/04
4
3
2
1
60
40
0
I
II
III IV
V
VI VII VIII IX
X
XI XII
I
II
Gospić
V
VI VII VIII IX
X
XI XII
X
XI XII
X
XI XII
8
61/90
7
64/90
170
91/05
6
91/04
3
Qaverage (m /s)
190
150
130
110
90
Slika ... Godišnji hod oborina u Pagu
70
5
4
3
2
1
50
0
I
II
III IV
V
VI VII VIII IX
X
XI XII
I
II
III IV
Ličko Lešće
61/90
140
91/05
Qaverage (m3/s)
160
120
100
80
60
40
I
II
III IV
V
V
VI VII VIII IX
GACKA - Vivoze
180
P ( mm )
IV
BOGDANICA - Kolakovica
210
P ( mm )
III
VI VII VIII IX
X
XI XII
Figure 5 Rainfall – monthly variations
24
22
20
18
16
14
12
10
8
6
4
78/90
91/03
I
II
III IV
V
VI VII VIII IX
Figure 6 Hydrograph – Lika area
12,0
Tavrage year
Taverage (61/03)
Taverage (61/87)
Taverage (88/03)
Poli. (Tavrage year)
11,5
Taverage °C
11,0
10,5
10,0
9,5
9,0
8,5
1961
1964
1967
1970
1973
1976
1979
Figure 7 Mean annual air temperature – Djurdjevac
1982
1985
1988
1991
1994
1997
2000
2003
13,0
Taverage year
Taverage (61/03)
Taverage (61/87)
Taverage (88/03)
Poli. (Taverage year)
12,5
Taverage °C
12,0
11,5
11,0
10,5
10,0
9,5
1961
1964
1967
1970
1973
1976
1979
1982
1985
1988
1991
1994
1997
2000
2003
Figure 8 Mean annual air temperature – Donji Miholjac
10,5
Taverage year
Taverage (61/05)
Taverage (61/87)
Taverage (88/05)
Poli. (Taverage year)
10,0
Taverage °C
9,5
9,0
8,5
8,0
7,5
1961
1964
1967
1970
1973
1976
1979
1982
1985
1988
1991
1994
1997
2000
2003
Figure 9 Mean annual air temperature – Gospić
CONCLUDING DISCUSSION
The conducted examinations indicate a presence of change within yearly precipitation and
watercourse in Croatia, while there is no significant change in the total yearly water quantity.
The observation of the mean yearly temperatures indicates an increase in the last 20 years.
Noticed changes influence the agriculture and water resources management. The Lika area is
rich in precipitation, but their yearly schedule is not favourable because of the redistribution
of precipitation and it becomes more unfavourable. The average yearly temperature is
systematically increasing, but also the absolute low extremes are getting to be even lower. The
examination of precipitation and air temperature, along with the river discharge, indicate that
systematic, long term and quality meteorological and hydrological observations needed as advised by
World Meteorological Organization.
References:
1. Measurement data, Meteorological and Hydrological Service of Croatia
2. M.Beraković: Climate and hydrologic characteristics, in Irrigation plan for districts Lika, Primorje
and Drava, Elektroprojekt, Zagreb, 2006/2007
Professor Boris Beraković, doctor of sciences, professor at the Faculty of Civil Engineering,
University of Zagreb, 40 years of experience in hydroelectric and water resources planning, project
evaluation, general planning and hydraulic design for hydroelectric and river control structures,
environmental studies. He has a long-time experience with Elektroprojekt Consulting Engineers prior
to the university career.
Marija Beraković, graduate geodetic engineer, is working in the field of hydrology for over 30 years,
mainly on the multipurpose river basin development studies, hydroelectric power plants, irrigation
projects and environmental studies. She has a long-time experience with Elektroprojekt Consulting
Engineers and Croatian Water Resources Management Authority.
Ksenija Cesarec, Master of Science, hydrologist, head of Hydrological Research and Forecasting
Department in Hydrology Division in Meteorological and Hydrological Service of Croatia., 37 years
of experience in hydrology studies, especially in water balance and long time series analysis. She is
working in project of climate change in Croatia. Few years ago started with revising environmental
studies as a member of a government commission for field of hydrology.