The impact of human activities on drought and flood severity across the U.S.

Xiaogang He1, Yoshihide Wada2, Niko Wanders3, Justin Sheffield4

1Princeton University2 International Institute for Applied Systems Analysis

3Utrecht University4University of Southampton

Human Interventions (HIs)

Land use changeLand use change

Groundwater pumping

Irrigation Reservoir/Dam

Water abstraction

Drought and human activities

Meteorological(Rainfall deficiency)

Agricultural(Soil moisture deficiency)

Hydrological(Streamflow deficiency)

DROUGHT

Climate Variability

Human Interventions (HIs)

Drought and human activities

Meteorological(Rainfall deficiency)

Agricultural(Soil moisture deficiency)

Hydrological(Streamflow deficiency)

DROUGHT

Land use changeLand use change

Groundwater pumping

Irrigation Reservoir/Dam

Water abstraction

Climate change + Climate VariabilityAttribution of HIs ➙ Drought Resilience?Scientific Questions:

① Can we quantitatively assess how of humaninterventions (HIs) contribute to U.S. (hydrological) drought risk?

② Where do HIs and where do they ?

③ What are the between anddue to HIs (e.g., reservoir operation)?

④ How does this compare with impacts on risk?

Methodology: PCR-GLOBWB model

• Simulation period• 1980-2016• 5 year spin up

• Resolution• 5 min, ~10 km

• Input forcing• NLDAS2, Prec, T

VSControl Experiment

• Only natural variability

Contrast Experiments

• Include different types of human activities (e.g., irrigation, reservoir, sectoral water use)

Human Intervention Data

Reservoir capacity Irrigation area

Sectoral water use

Industrial

Domestic

Distribution of Power Stations

Wada et al. (2016)

IrrigationDomestic water use

Industrial water use

Livestock water use

Reservoir operation

Groundwater pumping

Natural ✗ ✗ ✗ ✗ ✗ ✗Human ✓ ✓ ✓ ✓ ✓ ✓

Irrigation(+Reservoir+GW) ✓ ✗ ✗ ✗ ✓ ✓

Irrigation(-Reservoir+GW) ✓ ✗ ✗ ✗ ✗ ✓Non-Irrigation

(+Reservoir+GW) ✗ ✓ ✓ ✓ ✓ ✓Non-Irrigation(-Reservoir+GW) ✗ ✓ ✓ ✓ ✗ ✓

Experiment design

ScenariosActivities

☆

☆☆

☆

Drought severity(Standardized drought deficit volume (StDef))

Drought duration

Drought CharacteristicsSt

ream

flow

(m3 /

s)

Duration

Deficit (severity)

Impacts on floods characterized by standardized excess (StExcess)

JJA

DJF

Intensification

Alleviation

Results - Relative contribution to Drought Severity

All Human activitiesMAM

SON

%

-10

-30

-50

-70

-90

10

30

50

70

90

Alle

viat

e

Results – Irrigation versus Non-irrigation Interventions

High plains

Mississippi embayment

Columbia plateau

Snake river

Central valley

Edwards-Trinity aquifer

JJA

DJF

Irrigation%

-10

-30

-50

-70

-90

10

30

50

70

90

Alle

viat

e

%

-10

-30

-50

-70

-90

10

30

50

70

90DJF

JJA

Non-Irrigation%

-10

-30

-50

-70

-90

10

30

50

70

90

Alle

viat

e

Results - Does drought travel downstream?D

owns

tream

Intensify

All water useIrrigation

Non-Irrigation25%

Median75%

Dow

nstre

am

Intensify Intensify

Dow

nstre

amIntensify

Dow

nstre

am

Droughts

Results - Comparing with HI impacts onFlood Severity

Alle

viat

e

%

Alle

viat

e

Floods

%

Comparing Drought and Flood Downstream Effects

All water useIrrigation

Non-Irrigation25%

Median75%

FloodsDroughts

• Impacts on droughts are much higher and tend to have stronger downstream effects.

• Floods tends to be alleviated downstream

Summary

Using a macroscale hydrological and water resources model, we tryto unravel the relative contribution of human interventions todrought and flood severity over the US.

Irrigation reduces hydrological drought in areas of intensive irrigation,while shallow groundwater pumping can increase hydrologicaldrought. Non-irrigation water use has more spatially diverse impacts.

Downstream accumulation effects add another layer of complexity toassess the impacts of HIs on drought severity. Droughts are not justlocal.

Floods are also affected: mostly intensification but less relative impact

Work needed to corroborate with ground observations andknowledge

Water source to meet different demand -Surface water abstraction

0.001

0 0.002

0.003

0.004

0.005

0.01

0.02

0.03

0.04

0.05

0.01m/month

All human activities

Irrigation water use

Non-Irrigation water use

Water source to meet different demand -Non-fossil GW abstraction

0.001

0 0.002

0.003

0.004

0.005

0.01

0.02

0.03

0.04

0.05

0.01m/month

All human activities

Irrigation water use

Non-Irrigation water use

Water source to meet different demand -Fossil GW abstraction

0.001

0 0.002

0.003

0.004

0.005

0.01

0.02

0.03

0.04

0.05

0.01m/month

All human activities

Irrigation water use

Non-Irrigation water use