Rainbow water: rainfall, the water
cycle, forests and trees
9.00 Welcome addresses (Prof. Joachim von Braun, ZEF)
Block A New scientific insights // chaired by Grace Villamor (ZEF)
9.15 Rainbow water, the missing colour. Meine van Noordwijk (ICRAF)
9.35 Precipitation sheds, Patrick Keys
9.55 What trees can tell us about climate variability and change. Aster Gebrekirstos
10.05 The new West Africa climate centre and this agenda. Manfred Denich& Paul Vlek
Block B How does this relate to current climate policies and negotiations // chaired
by Bruno Locatelli (CIFOR)
10.30 Need for climate policy beyond mitigation and adaptation. Peter Minang
10.40 Discussant comments. Bruno Verbist (European Forestry Institute)
10.45 Discussion on relevance for new, more regional climate negotiations on land
cover and water balance
Block C Priorities for linking this emerging science to policy action in climate
policies and negotiations chaired by Henry Neufeldt (ICRAF)
11.05-11.40 Brainstorm groups
11.40-11.50 Plenary reporting
11.50-12.00 Closing remarks

CRP6: Forests, Trees and Agroforestry:
livelihoods, landscapes and governance

Rainbow water, the
•Rainbow =Recycled Atmospheric Inputs Now Bene-
fitting our Water-supply
missing colour
Meine van Noordwijk (ICRAF)
• Blue water: traditionally hydrology Rainbow wa-
studies water flow in rivers, its use for ter closes the
irrigation, industrial & domestic uses hydrological
water shortage & floods cycle, adds
• Grey water: added focus on pollution, the concept
cleansing and re-use water shortage of terrestrial
relates to ‘quality’ evapotranspi-
• Green water: realized that water use in ration as
‘upper watersheds’ is increased by ‘recycling’
forests & trees

> >
The holistic forest+tree the world world
The foresters’ view of view of the
Source: Global tree cover inside and outside forest, according to the Global Land Cover 2000
dataset, the FAO spatial data on farms versus forest, and the analysis by Zomer et al. (2009)

Forest and tree cover transitions: a unifying concept
across CRP6
X-linkage of
Temporal Spatial Institutional
actions in
pattern pattern challenge
landscape

Beyond variation in tree cover, we also need variation in
‘pattern’:
re- and afforestation
Fields,fallow, forest mosaic
Farm fo-
Plantations
restry, Fields,
agrofo- Forests
rests & Parks
deforestation
Sharing Sparing
Integrate Segregate

Solar radiation and Green-House Gas effect
Vegetation effects on
rainfall triggering
Macro- Teleconnections of
rainfall with sea sur-
face temperature
Rainfall pattern&intensity Meso-
Local tree cover: wind-
breaks, shade trees
Temperature, humidity,
windspeed, incoming
Micro - Plant
growth
radiation, potential eva-
potranspiration at the level
climate Water supply
of plants or animals buffered by soil

o
C
In the control simulation (FOREST), we consider
a maximally forested world, while in the second
simulation (GRASS) all forests are replaced by
grasslands.

Coarsening of pattern: segregate

Global CO2, CH4, N2O
climate
GCM’s Ocean tempe- emissions
El Nino, IOD
ratures
Rainfall in
space & time
SpatRain,
TempRain
Land use: Wanulcas
•plant production
•pathways of water
•timing of riverflow
GenRiver,
FlowPer
River flow in Upstream livelihoods
space & time RUPES/PRESA
Downstream ,, ,,

Global CO2, CH4, N2O
climate
GCM’s Ocean tempe- emissions
El Nino, IOD
ratures
Rainfall in Cloud formation
space & time
SpatRain,
TempRain
Land use: Wanulcas
•plant production
•pathways of water
•timing of riverflow
GenRiver,
FlowPer
River flow in Upstream livelihoods
space & time RUPES/PRESA
Downstream ,, ,,

Most studies have so far taken the
global climate as ‘exogenous’ and
started hydrology with actual patterns
of rainfall
• Some recent literature suggests
that there is more to it…

Two schools of thought in the forest water debate:
‘supply-’ and the ‘demand-side’
…the generally beneficial rela- …trees can redu-
tionship between forest cover ce runoff at the
and the intensity of the hydro- small catchment
logic cycle. scale.
Ellison D, Futter MN, Bishop K, 2011.On the forest cover–water yield debate: from demand- to supply-side
thinking. Global Change Biology, doi: 10.1111/j.1365-2486.2011.02589.x

Key points Ellison et al.
• The ‘short cycle’ rainfall can contribute 1/5 – 2/3’s
of rainfall depending on location
• About 1/3 of the ‘short cycle’ originates within the
(large) watershed, the rest is from outside
• Increased tree water use contributes to ‘intensity
of hydrological cycle’ and may not have to be
counted as ‘loss’ from a downstream perspective
Comments:
• The same would hold for wetlands, irrigation agri-
culture, use of ‘sprinklers’
• Global increase in water use for irrigated areas
matches increased supply by ‘deforestation’

Where
does
the Bosilovich MG,
precipi- Schubert SD (2002)
Water vapor tracers
table as diagnostics of
water in the regional hydro-
24-57%
rainfall logic cycle. Journal
‘short cycle’ of Hydrometeorolo-
come
origins gy, 3, 149–165.
from?

Ellison D, Futter MN,
% of rainfall derived from ‘short cycle’ Bishop K, 2011.On the
forest cover–water
terrestrial origins(recalculated from Basilovich et al.) yield debate: from
demand- to supply-
37% 58% 30% 68%
side thinking. Global
Change Biology, doi:
10.1111/j.1365-
2486.2011.02589.x
Approximately
a third comes
from ‘local’
42%
sources
40%
41% 46% 22%
1) Mackenzie river basin, 2) Mississippi river basin, 3) Amazon river basin, 4) West Afri-ca, 5)
Baltics, 6) Tibet, 7) Siberia, 8) GAME (GEWEX Asian Monsoon Experiment) and 9) Huaihe river
basin.

Terrestrial source areas (‘short cycle’) combine with
oceanic (‘long cycle’) in a complex pattern of
‘teleconnections’
Areas with high sea surface temperatures (SST) act
as source areas of oceanic water vapour, areas with
high ET rates as terrestrial ones, but their link to
rainfall in any area depends on dominant wind
patterns
Beyond the ‘El Nino’ (ENSO) effect, the ‘Indian
Ocean Dipole’ (IOD) and Sea Surface Temperatures
(SST’s) in many areas are now know to correlate
with rainfall

C: unimodal
Strong
No ENSO ENSO
response response
Medium
ENSO
response
B: bimodal
A: unimodal

Fig. 1. Annual rainfall anomaly (vertical bars) over the West African Sahel (13–20◦N,
15◦W–20◦E) from 1950 to 1998: (A) observations
Bruijnzeel LA (2004) Hydrological functions of
tropical forests: not seeing the soil for the trees?
Agriculture, Ecosystems and Environment, 104, Zeng, N., Neelin, J.D., Lau,
185–22 K.M., Tucker, C.J., 1999.
Enhancement of interdecadal
climate variability in the Sahel
by vegetation interaction.
Science 286, 1537–1540

Bruijnzeel LA (2004) Hydrological
functions of tropical forests:
not seeing the soil for the trees?
Agriculture, Ecosystems and
Environment, 104, 185–22
Model with atmosphre
& ocean interactions
(SST influences
accounted for)
Adding land
characteristics: (albedo,
soil moisture status)
Adding vegetation
characteristics, with
recovery time-lags
Zeng, N., Neelin, J.D., Lau,
K.M., Tucker, C.J., 1999.
Enhancement of interdecadal
climate variability in the Sahel
by vegetation interaction.
Science 286, 1537–1540

Fig. 1.
Geography of
the regions
where the
dependence of
precipitation
P on distance x
from the source of
moisture was
studied.

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

Why India and China should invest in draining the Sudd and
letting the water evaporate in Egypt in stead… and why
West Africa should be opposed to it

Deforesting
Myanmar
will reduce
rainfall in
China

South Africa’s
concept of pay-
ments for tree
plantations that
evaporate water
at above-average
rates, can not be
transferred to E.
Africa, where
such evapotrans-
piration is likely to
return as rainfall.

The transects
that Makarieva
& Gorshkov
(2007) studied
did not related
to main mois-
ture flux vector
of van der Ent
c.s.
Fig. 1.
Geography of
the regions
where the
dependence of
precipitation
P on distance x
from the source of
moisture was
studied.

Makarieva &
Gorshkov pro-
pose a ‘strong’
version of the
biotic effect
where forests
generate wind
& moisture
transport

Dryland agricultural areas where more than 50% of
rainfall is derived from terrestrial recycling
Sahel
Keys PW, van der Ent RJ, Gordon LJ, Hoff H, Nikoli R and Savenije HHG,
2012. Analyzing precipitationsheds to understand the vulnerability of
rainfall dependent regions, Biogeosciences, 9, 733–746

Land + Atmosphere as hydro-
logically open system
7 domains of hydrological
VOL + EL = PL influence of trees and forests:
‘long cycle’ ‘short cycle’ 1. Enhanced EL means
increased precipitation
2. Triggering precipitation
3. P partitioning over Q and
Dark Eintercept plus ΔS
Green
water 4. ΔSL partitioning over Evarious
and Q
Blue
water 5. Q dynamics influenced by
Light river & riparian zone
Green 6. Q use for irrigation
water
7. Q use for domestic + in-
Brown
water
dustrial use & recycling of
waste water

Rainbow water
Precipitable at- ~40% ES1: buffering of
waterflows rela-
mospheric water tive to incoming
Dark green Land rainfall, securing
water quality of blue
Rainfall use
~60% water flows
Rainfall – Recycling fee
Water ES fee (ES1)
Blue River Water delivery fee
water Water cleaning fee (ES2)
flow
Light
green
Global climate Water water
change * geo- use
graphy ES2: Cleaning of
waster water to
Recycled achieve quality
Grey/Brown water flows standards for re-
Oceans use

Regional water balance:
Vi+1 – Vi = ΔSv = Qi = Pi – Ei + ΔSw,i
At the ocean land-interface
V
Water and at any distance from the
ocean, incoming water
vapour in
the air mass vapour flow (V) equals P E
outgoing river flow Q
desert
Rainfall margin Sw
Threshold for
natural forest
forest
edge
Q
Increasing distance from the ocean – land interface
Evapo-transpiration Patch-level water
river balance:
tr. to
Con tive P = Q + E + Sw
a At patch level &
ul flow
m r annual scale:
Cu ive
r P=E+Q

• Current international climate policy is built on the
concept of ‘macro-climate’ change through CO2 and other
greenhouse gas emissions
• Land use and land use change does contribute to
emissions and hence is part of macro-climate change
• But, it also has a direct micro- and meso-climatic effect on
temperature, humidity, windspeed – and even on rainfall
• Such mesoclimatic effects of tree cover work within an
annual hydrological cycle, without the timelags of
atmospheric policies
• They operate at regional rather than global scale and
require new types of negotiations

Conclusions:
1.The forest-climate discourse is overly
carbonized
2.Micro- and mesoclimatic influences of
forests & trees have too long been
ignored by scientists and remain
undervalued in the climate policy arena
3.Recent findings on rainbow water
hydrology point to teleconnections of
geopolitical importance

Mesoclimatic impacts of land cover
change: research agenda V M A
• Quantifying land cover change, focus on trees . X .
• Understanding drivers of tree cover change and . X .
‘what it takes’ to influence them
• Multiplying change in land cover with ‘water recy- . X .
cling activity factors’ in parallel to ‘GHG emission
factors’ for GHG accounting
• Linking land cover change feedbacks into global/ X . X
regional climate change models (beyond statistical
downscaling routines)
X X X
• Scenario studies on economy/environment interface
• International/regional negotiations on change X X X
pathways

Geopolitics of climatic teleconnections,
payments for ecosystem services and pri-
cing of water: four colours of water
• Rainbow water is the source of all green, blue and
brown water flows
• A large share of PES is linked to water delivery with
direct link between ‘goods’ and ‘services’
• New insights into rainfall generation suggest
substantial (~40%) role for short cycle rain
• Teleconnections on short cycle rain from green water
use suggest complex political relations
• PES funds derived from blue water use need to
balance brown, green and rainbow water allocations

‘Mesoclimatic’ effects in the UNFCCC
• The UNFCCC has been framed around the ‘macro-
climatic’ emission concept; hence mitigation
implies reducing emissions and not reducing other
anthropogenic change of climatic variables (incl.
albedo, hydrological cycle links)
• The UNFCCC concept of ‘adaptation’ is about
reducing human & ecosystem vulnerability in the
face of anthropogenic climate change: it can
(implicitly) include other pathways for anthro-
pogenic climate change

http://wallpaperswide.com/rainbow_water-
wallpapers.html
Rainbow water clo-
ses the hydrological
cycle, adds the con-
cept of terrestrial
evapotranspiration
as ‘recycling’