[PP13] Hydrological droughts of groundwater 
[PP13] Hydrological droughts of groundwater
Key message
Frequency of groundwater drought is increasing in recent decades in alluvial aquifers. 8 out of 10 years with highest intensity of groundwater drought in period 1981-2023 occurred after year 2000. Groundwater droughts with higher intensity is characteristic for winter while milder groundwater droughts mostly occur at the beginning of autumn. Groundwater drought intensity is also increasing seasonally with time between June and September when groundwater use is pronounced.
Charts
Figure PP13-1: Annual average of standardized groundwater level index (SGI) on selected measuring stations
Sources:
Hydrologic database ARSO, Slovenian Environment Agency, 2024 ()
Table PP13-2: Percentage of measuring stations with groundwater drought detection in intergranular aquifers by individual years
Sources:
Source: Hydrologic database ARSO, Slovenian Environment Agency, 2024 ()
| Extremely dry (SGI <-2)[%] | Severely dry (-2 <SGI <-1.5)[%] | Moderately dry (-1.5 <SGI <-1)[%] | Mildly dry ( (-1 < SGI < 0)[%] | |
|---|---|---|---|---|
| 1981 | 1.06 | 4.26 | 8.51 | 24.47 |
| 1982 | 1.96 | 2.94 | 6.86 | 25.49 |
| 1983 | 5.83 | 8.33 | 16.67 | 22.50 |
| 1984 | 0 | 3.92 | 9.80 | 23.53 |
| 1985 | 1.59 | 4.76 | 11.90 | 20.63 |
| 1986 | 0 | 1.63 | 8.94 | 20.33 |
| 1987 | 0.92 | 0.92 | 10.09 | 21.10 |
| 1988 | 1.05 | 2.11 | 10.53 | 26.32 |
| 1989 | 2.44 | 8.94 | 17.07 | 21.95 |
| 1990 | 0.93 | 3.70 | 14.81 | 28.70 |
| 1991 | 0.91 | 1.82 | 2.73 | 22.73 |
| 1992 | 0 | 2.75 | 19.27 | 27.52 |
| 1993 | 2.31 | 15.38 | 23.08 | 23.85 |
| 1994 | 0 | 1.06 | 5.32 | 27.66 |
| 1995 | 0.81 | 1.61 | 6.45 | 21.77 |
| 1996 | 0 | 1.04 | 1.04 | 11.46 |
| 1997 | 1.05 | 7.37 | 20 | 32.63 |
| 1998 | 0 | 3.42 | 14.38 | 21.23 |
| 1999 | 0 | 1.72 | 7.76 | 18.97 |
| 2000 | 0 | 4.17 | 22.92 | 31.25 |
| 2001 | 1.69 | 11.02 | 15.25 | 26.27 |
| 2002 | 6.48 | 20.37 | 21.30 | 23.15 |
| 2003 | 8.33 | 24.07 | 26.85 | 25.93 |
| 2004 | 4.27 | 8.55 | 11.11 | 24.79 |
| 2005 | 0 | 1.59 | 12.70 | 24.60 |
| 2006 | 3.03 | 6.06 | 15.91 | 21.97 |
| 2007 | 3.85 | 7.69 | 23.08 | 29.81 |
| 2008 | 0 | 1.05 | 10.53 | 32.63 |
| 2009 | 0.81 | 1.63 | 9.76 | 21.14 |
| 2010 | 0 | 0 | 6.67 | 22.86 |
| 2011 | 1.60 | 10.40 | 22.40 | 24.80 |
| 2012 | 4.88 | 18.70 | 23.58 | 23.58 |
| 2013 | 0 | 2.11 | 7.04 | 19.01 |
| 2014 | 0 | 0 | 0 | 15.56 |
| 2015 | 0 | 3.19 | 12.77 | 29.79 |
| 2016 | 0 | 3.06 | 14.29 | 30.61 |
| 2017 | 0.91 | 8.18 | 20 | 28.18 |
| 2018 | 0.78 | 2.33 | 9.30 | 22.48 |
| 2019 | 1.87 | 8.41 | 20.56 | 28.97 |
| 2020 | 1.77 | 9.73 | 20.35 | 27.43 |
| 2021 | 0 | 5.26 | 15.79 | 27.19 |
| 2022 | 7.77 | 16.50 | 24.27 | 26.21 |
| 2023 | 0 | 0 | 2.21 | 16.91 |
Figure PP13-3: Percentage of measuring stations with groundwater drought detection in intergranular aquifers between June and September by individual years
Sources:
Source: Hydrologic database ARSO, Slovenian Environment Agency, 2024 ()
| Extremely dry (SGI <-2)[%] | Severely dry (-2 <SGI <-1.5)[%] | Moderately dry (-1.5 <SGI <-1)[%] | Mildly dry ( (-1 < SGI < 0)[%] | |
|---|---|---|---|---|
| 1981 | 2.08 | 2.08 | 4.17 | 22.92 |
| 1982 | 0 | 0 | 5.56 | 40.74 |
| 1983 | 0 | 5.88 | 17.65 | 43.14 |
| 1984 | 0 | 1.75 | 1.75 | 24.56 |
| 1985 | 0 | 1.27 | 5.06 | 22.78 |
| 1986 | 0 | 1.33 | 0 | 18.67 |
| 1987 | 0 | 0 | 4.69 | 18.75 |
| 1988 | 0 | 0 | 3.64 | 27.27 |
| 1989 | 0 | 0 | 0 | 20.90 |
| 1990 | 0 | 0 | 5.08 | 42.37 |
| 1991 | 0 | 0 | 2.70 | 21.62 |
| 1992 | 0 | 3.13 | 25 | 45.31 |
| 1993 | 5.26 | 28.07 | 40.35 | 22.81 |
| 1994 | 0 | 0 | 3.64 | 38.18 |
| 1995 | 0 | 0 | 0 | 14.29 |
| 1996 | 0 | 0 | 0 | 7.94 |
| 1997 | 0 | 1.96 | 3.92 | 52.94 |
| 1998 | 0 | 3.95 | 18.42 | 34.21 |
| 1999 | 0 | 0 | 0 | 13.16 |
| 2000 | 0 | 6.67 | 35.56 | 53.33 |
| 2001 | 0 | 0 | 8.93 | 46.43 |
| 2002 | 0 | 9.23 | 18.46 | 32.31 |
| 2003 | 9.43 | 37.74 | 39.62 | 9.43 |
| 2004 | 0 | 0 | 2.99 | 37.31 |
| 2005 | 0 | 0 | 1.12 | 30.34 |
| 2006 | 0 | 1.54 | 1.54 | 24.62 |
| 2007 | 3.51 | 7.02 | 29.82 | 42.11 |
| 2008 | 0 | 0 | 3.08 | 23.08 |
| 2009 | 0 | 1.32 | 1.32 | 18.42 |
| 2010 | 0 | 0 | 10.77 | 30.77 |
| 2011 | 0 | 0 | 13.33 | 62.22 |
| 2012 | 0 | 20 | 32.73 | 32.73 |
| 2013 | 0 | 3.90 | 6.49 | 27.27 |
| 2014 | 0 | 0 | 0 | 18.18 |
| 2015 | 0 | 0 | 8.33 | 41.67 |
| 2016 | 0 | 0 | 3.70 | 44.44 |
| 2017 | 1.47 | 7.35 | 25 | 41.18 |
| 2018 | 0 | 0 | 1.39 | 22.22 |
| 2019 | 0 | 1.54 | 9.23 | 36.92 |
| 2020 | 1.56 | 9.38 | 14.06 | 34.38 |
| 2021 | 0 | 0 | 7.14 | 42.86 |
| 2022 | 13.33 | 15 | 26.67 | 33.33 |
| 2023 | 0 | 0 | 0 | 7.14 |
Methodology
Date of data source summarization
Other sources and literature
- Agencija RS za okolje, 2018. Ocena podnebnih sprememb v Sloveniji do konca 21. stoletja. Ljubljana, november 2018.
- Kobold, M., 2003/2004. Hidrološka suša slovenskih vodotokov v obdobju 2000 – 2002. Ujma, 23: 128-135.
- Mckee, T. B., Doesken, N. J. & Kleist, J., 1993: The relationship of drought frequency and duration to time scales. Eight Conference on Applied Climatology: 179–184.
- Programme (IDMP), Integrated Drought Management Tools and Guidelines Series 2. Geneva.
- RSRS – Računsko sodišče Republike Slovenije, 2019: Revizijsko poročilo, Učinkovitost dolgoročnega ohranjanja virov pitne vode. Številka: 320-7/2017/30. Medmrežje: http://www.rs-rs.si/fileadmin/user_upload/Datoteke/Revizije/2019/PitnaVoda/PitnaVoda_RSP.pdf
- Sheffield J., and Wood E.F., 2011: Drought: past problems and future scenarios. Earthscan, 210 pp.
- World Meteorological Organization (WMO) and Global Water Partnership (GWP), 2016: Handbook of Drought Indicators and Indices (M. Svoboda and B.A. Fuchs). Integrated Drought Management. Medmrežje: https://library.wmo.int/doc_num.php?explnum_id=3057