Presentation by Meine van Noordwijk at ICRAF side event on ecological rainfall infrastructure at the Paris COP21

1. Ecological rainfall infrastructure: investment in
trees for sustainable development
Ecological rainfall infrastructure, Rio Pavillion
COP PARIS 02-12-2015
Meine van Noordwijk
Chief ScienDst, World Agroforestry
Centre (ICRAF); Professor of Agro-
forestry, Wageningen University
Long cycle:
oceans
to land
Short cycle:
Land to land

3. Forest and water – big picture on ‘cool forests’
Q = P - E ± ΔS
Stream flow (blue
water): flow persis-
tence depends on
watershed health, as
does water quality
PrecipitaDon of ‘rainbow
water’: 60% of rainfall over
land derives from oceans, 40%
from vegetaDon on land
EvapotranspiraDon
(green water use)
leads to air cooling,
trees use 100-200
mm/year more than
short vegetaDon
Soil water storage
(‘sponge effect’)
depends on soil
depth and structure

4. Blue water
streamflow
Rainfall triggering
conditions
Precipi-
tation
Rainbow water Atmospheric transport
Soil & ground-water
buffering
GreenwaterET
evapotranspiration
Precipi-
tation
GreenwaterET
evapotranspiration
Blue water
streamflow
Soil & ground-water
buffering

5. van der Ent RJ, Savenije
HHG, Schaefli B, Steele-
Dunne SC, 2010. Origin
and fate of atmospheric
moisture over
conDnents. Water
Resources Research 46,
W09525,
E/P
Pfrom Et/P

6. • Trees consume water
• Trees recycle water
• Trees help store water by
changing soil to be
a more effecDve buffer
• Streamflow from healthy
catchments with forests
and trees is more gradual
Higher evapotranspi-
raDon means more
cooling effect
Higher evapotranspi-
raDon means more
atmospheric water
vapour
Prevailing
winds
BioDc-pump-induced
air flows?
Oceanic input
Biological precipitaDon
triggers? Rainfall
Downstream water
use, livelihoods risks
and benefits
Scien1-
fic
debate
Downstream and
downwind benefits of
watershed restoraDon

7. Lightning
BNF Denitrifiers
Long cycle rain
BRG ET

9. Stem-flow
Through
-fall
Rainfall Cloud
interception
Lateral
outflows
(interflow) Recharge
Soil surface
evaporation
Transpiration
Canopy water
evaporation
Uptake
Quick-
flow
Base flow
{
Surface
run-on
Surface
Run-off
Streams
& river
Litter layer
Sub-
surface
lateral
inflows
Infil-
tra-
tion
Percolation
Canopy
inter-
ception

10. Cooling effect of E
Foresters & farmers
managing tree cover:
ET translated into tree,
crop and pasture
producDvity
New BRG-science
Rainbow water closes
the hydrological cycle
Hydrologists:
Q, Blue water
implies focus
on stream-
flow (floods,
drought, use
as irrigaDon
source)
Tree ecophy-
siologists: Et,
Green water
implies focus
on use of wa-
ter by vegeta-
Don, compe-
Dng with what
enters streams
Soil scien1sts:
ΔS, Sponge
effect focus on
buffering by
soil with good
infiltra-Don
and deep root
systems
Landscape ecologists: scaling from patch, via hillslopes to
watersheds in relaDon to human land use
Climatologists: P,
PrecipitaDon (rainfall)
sourced from oceans +
land, global circulaDon

11. Decarbonizing the debate on forests,
trees and climate: cool trees
Trees make it cooler ,
help with rainfall and
keep the soil moist
UNFCCC: global climate
change depends on
greenhouse gas emissions
This carbon thing is
hard to understand,
we can’t see it…