Why meteorological drought indices should not be used to study hydrological anomalies Anne F. Van Loon, Henny A.J. Van Lanen and Adriaan J. Teuling With contributions of Marjolein Van Huijgevoort, Niko Wanders and Erik Tijdeman
2003 drought impact in Europe: - Forest fires - Food production - Transport - Health - Ecosystems
Amazon - 2010
Africa - 2011
DROUGHT is
DROUGHT is - below normal water availability - with natural causes - a recurring and worldwide phenomenon
meteorological situation
low P
meteorological drought
precipitation deficiency
soil moisture drought
hydrological drought
socio-economic drought
low soil moisture
low groundwater storage
low discharge
impacts
precipitation
soil moisture
groundwater
discharge
time
Van Loon, 2013
precipitation
PROPAGATION
soil moisture
• • • •
groundwater
Lag Attenuation Pooling Lengthening
discharge
time
Van Loon, 2013
meteorological situation
low P
meteorological drought
precipitation deficiency
soil moisture drought
hydrological drought
socio-economic drought
low soil moisture
low groundwater storage
low discharge
impacts
How is SPI calculated?
For different time periods: 1, 3, 6, 12, 24, 36 months
Are meteorological drought indices used to study hydrological anomalies?
YES
Correlation between SRI (Standardised Runoff Index) and SPI in Amazon and Mississippi basins
Joetzjer et al. 2012, HESSD
Correlation between SDI (Streamflow Drought Index) and SPI in Evinos river basin (Greece)
Nalbantis and Tsakiris, 2009, WRM
Correlation between PDSI (Palmer Drought Severity Index) and SPI in several basins in China
Zhai et al. 2010, JoC
Should meteorological drought indices be used to study hydrological anomalies?
NO
Correlation between streamflows and SPI in the southwest of Hungary
Szalai et al. 2000, WMO report
global scale
Climate zones
From: Wanders et al. 2010
Meteorological drought indices
NO Hydrological drought indices
Wanders et al. in prep.
Van Huijgevoort et al., in press, JHM
Spatial drought development of two events for monthly precipitation, 3-month precipitation and runoff
Mid 1980s drought event in the Sahel
1976 drought event in Europe
Van Huijgevoort et al., in press, JHM
Mid 1980s drought event in the Sahel
Van Huijgevoort et al., in press, JHM
lag attenuation
pooling
lengthening
1976 drought event in Europe
Why meteorological drought indices should not be used to study hydrological anomalies Using: - Observations - Conceptual hydrological model - Drought analysis method
Why meteorological drought indices should not be used to study hydrological anomalies • Role of evapotranspiration
catchment scale
2003 drought (Switzerland)
Teuling et al., 2013, GRL
Teuling et al., 2013, GRL
Why meteorological drought indices should not be used to study hydrological anomalies • Role of evapotranspiration
Why meteorological drought indices should not be used to study hydrological anomalies • Role of evapotranspiration • Effect of temperature (and snow)
catchment scale Europe
precipitation
soil moisture
groundwater
discharge
time
temperature
snow
0°C
0°C
4 out of the 5 most severe drought events in Norway
2 out of the 5 most severe drought events in Spain
precipitation
soil moisture
groundwater
discharge Van Loon and Van Lanen, 2012, HESS
Is dat belangrijk?
Is dat belangrijk?
global scale
Climate zones
From: Wanders et al. 2010
Temperate climate
DROUGHT
Variable threshold level
precipitation
(based on percentile of duration curve)
soil moisture deficit
groundwater duration
discharge
time
standardised deficit [days]
Temperate climate
duration [days] Van Loon et al., in prep.
standardised deficit [days]
Temperate climate
duration [days] Van Loon et al., in prep.
standardised deficit [days]
Temperate climate
duration [days] Van Loon et al., in prep.
standardised deficit [days]
Temperate climate
attenuation
pooling & lengthening
duration [days] Van Loon et al., in prep.
Tundra climate
standarised deficit [days]
Steppe climate
duration [days]
duration [days]
Van Loon et al., in prep.
temperature
0°C
0°C
snow
precipitation
soil moisture
groundwater
discharge Van Loon and Van Lanen, 2012, HESS
Why meteorological drought indices should not be used to study hydrological anomalies • Role of evapotranspiration • Effect of temperature (and snow)
Why meteorological drought indices should not be used to study hydrological anomalies • Role of evapotranspiration • Effect of temperature (and snow) • Non-linear transformation in the subsurface
catchment scale Europe
deficit [mm]
duration [days]
Van Loon and Van Lanen, 2012, HESS
deficit [mm]
fast responding system
slow responding system
duration [days]
Van Loon and Van Lanen, 2012, HESS
global scale
Climate zones
From: Wanders et al. 2010
duration [days] Van Lanen et al., 2013, HESS
Why meteorological drought indices should not be used to study hydrological anomalies • Role of evapotranspiration • Effect of temperature (and snow) • Non-linear transformation in the subsurface
Why meteorological drought indices should not be used to study hydrological anomalies • • • •
Role of evapotranspiration Effect of temperature (and snow) Non-linear transformation in the subsurface Human influence
catchment scale Europe
Guadiana
Undisturbed period > calibration
Van Loon and Van Lanen, 2013, WRR
Disturbed period > extrapolation
Van Loon and Van Lanen, 2013, WRR
groundwater level
12 events with avg. duration of 11 months
model
3 events with avg. duration of 66 months in groundwater
Van Loon and Van Lanen, 2013, WRR
groundwater level
12 events with avg. duration of 11 months
model
3 events with avg. duration of 66 months in groundwater
Van Loon and Van Lanen, 2013, WRR
Why meteorological drought indices should not be used to study hydrological anomalies • • • •
Role of evapotranspiration Effect of temperature (and snow) Non-linear transformation in the subsurface Human influence
When can meteorological drought indices be used to study hydrological anomalies? •
• • •
In catchments where influence of temperature on anomalies is expected to be low > no snow climates In catchments where influence of evapotranspiration on anomalies is expected to be low > no warm climates In fast responding catchments > no storage in groundwater, wetlands and lakes In catchments where influence of humans on anomalies is expected to be low
When can meteorological drought indices be used to study hydrological anomalies? • On very long time scales, when effects of temperature and non-linear transformation in stores are averaged out
Van Huijgevoort et al., in press, JHM
meteorological situation
meteorological drought
soil moisture drought
hydrological drought
socio-economic drought
“rain” season
low P
“snow” season high T + low T or low P
precipitation deficiency
low soil moisture
low groundwater storage
low discharge
impacts
Thank you!
[email protected] ResearchGate: Anne Van Loon
