KAZALCI OKOLJA

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Total renewable groundwater quantity in the shallow aquifers of Slovenia in the hydrological year 2018 was above the long-term average period 1981–2010.


This indicator is expressed as annual groundwater recharge of shallow aquifers in a hydrological year (1 November–31 October) in all groundwater bodies for the entire territory of the Republic of Slovenia.

Groundwater is replenished by aquifer recharge, which is a complex process of water inflow into the subterranean saturated zone. Recharge is assessed by the regional water balance model and expressed as the height of water infiltrated into aquifers (mm) or the annual variability index (the 1981–2010 average = 100).

Droughts can have severe consequences for Europe’s ecosystems and citizens, and for many economic sectors, including agriculture, energy production, industry and public water supply. It is important to distinguish between different kinds of drought. A persistent meteorological drought (i.e. a precipitation deficiency) can propagate to a soil moisture (agricultural) drought affecting plant and crop growth, which may deepen into a hydrological drought affecting water resources, water quality and freshwater ecosystems. A river flow drought is characterised by unusually low river flow, which may result from a prolonged meteorological drought, possibly in combination with socio-economic factors.

 


Charts

Figure VD15-1: Assessment of shallow aquifer recharge in hydrological year 2018 by GROWA-SI model
Sources: 

Regional water balance model GROWA-SI (Forschungszentrum JÜLICH, Slovenian Environment Agency), 2019

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Figure VD15-2: Groundwater recharge of shallow aquifers - annual quantity deviations in 2018 from 1981 - 2010 average
Sources: 

Regional water balance model GROWA-SI (FZ JÜLICH, Slovenian Environment Agency), 2019

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annual average[mm]

deviation (mm)[mm]

deviation (%)[%]

period average 1981-2010[mm]

1971

229.27

-59.73

-20.67

289

1972

384.74

95.74

33.13

289

1973

268.57

-20.44

-7.07

289

1974

321.26

32.26

11.16

289

1975

309.23

20.23

7

289

1976

310.48

21.48

7.43

289

1977

307.87

18.87

6.53

289

1978

311.76

22.76

7.88

289

1979

385.20

96.20

33.29

289

1980

348.45

59.45

20.57

289

1981

265.85

-23.15

-8.01

289

1982

326.15

37.15

12.86

289

1983

206.95

-82.05

-28.39

289

1984

334.56

45.56

15.76

289

1985

327.17

38.17

13.21

289

1986

276.88

-12.12

-4.20

289

1987

340.07

51.07

17.67

289

1988

251.75

-37.25

-12.89

289

1989

269.81

-19.19

-6.64

289

1990

311.30

22.30

7.72

289

1991

301.62

12.62

4.37

289

1992

302.55

13.55

4.69

289

1993

256.43

-32.57

-11.27

289

1994

275.69

-13.31

-4.61

289

1995

335.00

46.00

15.92

289

1996

339.20

50.20

17.37

289

1997

252.96

-36.04

-12.47

289

1998

299.92

10.92

3.78

289

1999

313.62

24.62

8.52

289

2000

307.66

18.66

6.46

289

2001

272.77

-16.23

-5.62

289

2002

276.59

-12.41

-4.29

289

2003

183.78

-105.22

-36.41

289

2004

337.16

48.16

16.66

289

2005

282.46

-6.55

-2.26

289

2006

222.50

-66.50

-23.01

289

2007

242.83

-46.17

-15.98

289

2008

339.92

50.92

17.62

289

2009

320.93

31.93

11.05

289

2010

399.55

110.55

38.25

289

2011

174.29

-114.71

-39.69

289

2012

206.80

-82.20

-28.44

289

2013

333.30

44.30

15.33

289

2014

461.36

172.36

59.64

289

2015

300.76

11.76

4.07

289

2016

262.70

-26.30

-9.10

289

2017

266.30

-22.70

-7.85

289

2018

358.10

69.10

23.91

289

Figure VD15-3: Groundwater recharge of shallow aquifers - annual quantity deviations in 2018 from 1981 - 2010 average
Sources: 

Regionalni vodno-bilančni model GROWA-SI (FZ JÜLICH & Agencija RS za okolje), 2019

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Goals

Groundwater is traditionally the major source of drinking water in Slovenia, contributing most of the required quantities in the country. Slovenian groundwater sources exhibit high regional and seasonal variability and, lately, there has been a tendency toward more frequent and more pronounced extremes. This points to the possibility of a crisis in drinking water supply in the future.

The legislative basis for the preparation of the indicator is the EU Adaptation Strategy Package, which also aims to improve the data base for better decision-making in the field of adaptation to climate change. The followint actions are required:

  • improvement of groundwater quantity assessment, as well as forecasting and alarming in case of hydrological extremes, e.g. hydrological drought in aquifers;
  • identification of groundwater areas prone to frequent hydrological droughts;
  • improvement of groundwater management in the fields of drinking water supply and conservation of groundwater-dependent aquatic ecosystems.

The lowest recharged quantities as well as the highest variability in year-to-year groundwater recharge in shallow aquifers were recorded in groundwater bodies of northeastern Slovenia and in the Primorska region (Figure VD15-1). In the recent decade, the average recharge of aquifers in the Goričko region was 10-times lower than that of aquifers in the Julian Alps. Apart from this highly pronounced spatial variability, great variability over the course of time was recorded in the recent decade. Compared to the average for the 1981–2010 period, the index of annual groundwater recharge shows great variability, indicating high sensitivity of shallow aquifers in terms of groundwater quantity.

In the hydrological year of 2018, the total rechargeable groundwater quantity in shallow aquifers of Slovenia was markedly above the 1981–2010 average (Figure VD15-2). The average deviation for the entire territory of Slovenia is 24 %. The largest positive deviations from the average of the period 1981-2010 were in the groundwater body of the Mura Basin, where they also reach a 60% deviation. A larger positive deviation also occurs in the groundwater bodies Obala and Kras with Brkini. Elsewhere in Slovenia, the deviation ranges between 10 and 25 %. A slightly smaller negative deviation occurs in the west of Slovenia (up to -10%) and in the extreme northeast (up to -20%).



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