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Growing water scarcity in agriculture - future challenge to global water security By Professor Malin Falkenmark Stockholm International Water Institute and Stockholm Resilience Center


Why agriculture? 70 times more water than households 3000 kcal/p d /20 % anim prot --> 3500 l/p d or 1300 m3/p yr.


Analy&cal framework    

Two partitioning points: - land surface - root zone


Country water balance

Kenya


Water security - what risks to cope with?

Aim = successful management of water for - food……….green+ blue - humans…..blue

A. Green water risks B. Blue water risks C. Regional risks D. Global risks


A.  Green water-related risks links to agriculture


Risk 1. Too little annual rainfall *  par&cular  exposure  of  semi-­‐arid  zone      

From IWMI 2007

Rainfall changes around red line of critical importance for crop production impact


Risk 2. Dryspells

Dryspell >14 days during crop season

Number of dryspells during crop season > 14 days 4

Maradi Zinder Linear (Maradi)

3

3

Linear (Zinder)

2

2

1

1

0 1960

1970

1980 Year

1990

2000


Risk 3. Droughts famine

fourfold African vulnerability

nat.green

drought risk

degraded green

nat blue


Result: poor  yields  -­‐  why? RAIN

    •  huge  water  losses    -­‐  blue  water  loss    -­‐  green  water  loss  

•  poor  root  water   uptake  

1

green loss plant uptake

2

water partitioning

blue losses

3

Farming systems in Subsah. Africa


B. Blue water-related risks - competition - complexity


Risk1. : When population grows water crowding increases scale: 1 cube = 1 million cubic meter/yr 1 dot

= 100 persons


Risk 2: When demand grows water stress increases (from Kummu et al)

1900-2005

P/flow unit agr trade ---->

> 2000

1000-2000

irrig ----->

groundw ----->

600-1000


Result: River basin closure % demanddriven

vulnerable triangle 200 m3/p  yr     municipal/   industrial  use

1000 p/flow unit

p/flow unit population driven


C. Regional-scale risks carrying capacity overshoot


Country food water availability 2050 cropland water, km3/yr

Water requirement

1300 m3/p yr

Blue+ green

% of world pop a. 46 % b. 14 % c. 21 % d. 19 % --> Blue


Crrying capacity overshoot 2050 25 % yield gap closure 3000 kcal/p d 20 % animal food

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D. Global-scale risks Planetary Freshwater Boundary


Bloodstream of the biosphere Maximized cons use:

Atmosphere Sea

max 5000 km3/yr

.a Terrestrial Ecosystems

Ecosystem Goods/Services

Consumptive Use

.b

Society Waste Water Return Flows Water Withdrawals

Continents

Ecosystem Goods/Services

c.

Aquatic Ecosystems

Planetary Freshwater Boundary - env flow > 0


Water-security means coping with: A. Green water risks: crop water deficiency dryspells, drought, aridification

B. Blue water risks:

water crowding, water stress irrigation limitations, competing sectors environmental flow constraints, basin closure

C. Regional risks:

carrying capacity overshoot food trade

D. Global risks:

consumptive use constraints food, carbon-seq., fuelwood


Thank you! www.siwi.org

Growing water scarcity in agriculture – future challenge to global water security  

Professor Malin Falkenmark, Senior Scientific Advisor at Stockholm International Water Institute, Stockholm University, Sweden - Growing wa...

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