B1. Quantifying the role of AF in modifying watershed functions 

B1. Quantifying the role of AF in modifying watershed functions 

Starting from current practice in 'integrated watershed management' with participatory methods

• Biophysical Gains of Participatory Agroforestry: Evidence from Integrated Watershed Development Project, Hills II, India 

• Collective action in integrated soil and water conservation: the case of Gununo Watershed, Southern Ethiopia

Delving deeper into the biophysical processes• CONVERSION OF FOREST TO COFFEE-BASED AGROFORESTRY IN

INDONESIA: Litter layer, residence time, population density of earthworm and 

• Modelling water dynamics in coffee systems - Parameterization of a mechanistic model over two production cycles in Costa Rica. 

• Impacts of shade trees on hydrological services and erosion in a coffee AFS of Costa Rica: Scaling from plot to watershed 

• Tree roots anchoring soil and reducing landslide risk during high rainfall episodes as basis for adaptation and mitigation to climate change 

Scaling back up to the landscape• Buffering water flows through agroforestry management: quantifying the

influence of landscape mosaic composition and pattern 

Buffering water flows through agroforestry management: quantifying

the influence of landscape mosaic composition and pattern

Meine van Noordwijk, Betha Lusiana, Bruno Verbist 

Sustainable land use

Agroforestry

Hydrological Functions

Watershed management

‘Protec-tive

garden’

Trees, Soil,

Drainage

Stakehol-der nego-

tiation

Criteria & Indicators

Buffering water flows through agroforestry management: quanti-fying the influence of landscape mosaic composition and pattern

rainfall

lateral

outflow

percolation

surfaceevaporation

transpiration

canopy waterevaporation

uptake

quick-flow

baseflow

{

surface run-on

sub-surfacelateral

inflow

surface run-off

Stream:

stem-flow

through-fall

cloudinterception

rechargeinfiltration

Diagnostic Actions to remedy Spatial prioritization for program efficiency

Other benefits (Public) Fund

allocation

Improved watershed services?

% Forest cover Tree planting Qmax/ Qmin Buffered flow expec-tation, no floods

Diagnostic Actions to remedy Spatial prioritization for program efficiency

Other benefits (Public) Fund

allocation

Improved watershed services?

% Forest cover Tree planting Qmax/ Qmin Buffered flow expec-tation, no floods

Is Qmax/Qmin a suitable indicator?

• Maximum flow (Qmax) reflects the biggest rainfall event (minus infiltration)

• Minimum flow (Qmin) reflects the longest dry period (as long as groundwater was fully recharged at end of rains)

• The ratio of these two reflects climate variability – with potentially some impacts of landscape quality

We need real indicator of watershed condition, independent of weather

Basic Watershed Components

Base Flow

Groundwater

Sediment Loss

Rainfall

Overland Flow

River

Transpiration

Sub-surfaceflow

Water Input

Lateral Flows, Filters, Channels, & Storage

“pump”“pump”

“sponge”

“sponge”

Water Outputs

Buffering of flows at multiple scales

Contributing factors• Interception + canopy drip => half hour shift• Surface flow vs infiltration => 1-2 day shift• Flow conditions in river bed => few hours• Impoundments, wetland overflow areas => days• Spatial variability of rainfall => weeks• Lakes and man-made reservoirs => months,

rarely years

Precipitation = P

Evapotranspiration = ERiver flow = Q

Qquick Qslow Eveg Esoil EintercEirr

infiltration

interception

Esoil + Eveg

Einterc

Qslow

Qquick

Energy-limited Epotential

Signal modification along river

precipitation

1. Transmit water

2. Buffer peak rain events

3. Release gradually

4. Maintain quality

5. Reduce mass wasting

• Q/P=1-(E/P) QabAvg/PabAvg

• Qslow/P = (Pinf – ES+V)/P

• Qualout/Qualin

risk

Scaledependent

Point of inflection when landscape sponge reaches saturation

A. Cumulative rainfall, mm

Small effects of land use change relative to

interannual variability

Cumulative dry season flow = drying

out the sponge

Source: Xing Ma, Jianchu Xu & Meine van Noordwijk : Sensitivity of streamflow from

a Himalayan catchment to plausible changes in land-cover and climate

(submitted)

0

5

10

15

20

25

30

0 20 40 60 80 100 120 140Rainfall, mm day-1

Riv

er

flo

w, m

m d

ay

-1

1975-19811982-19881990-19981st quarter2nd quarter3rd quarter4th quarter

Way Besai

Mae Chaem

Wettest month in Mae Chaem is

approaching Way Besai

1 – slope of line = buffering indicator

Source: Xing Ma, Jianchu Xu & Meine van Noordwijk : Sensitivity of streamflow from a Himalayan catchment to plausible changes in land-cover and climate (submitted)

0

20

40

60

80

100

120

0 20 40 60 80 100 120

River today

Riv

er y

este

rday

19751985

1995

Flow persistence 0.75

Way Besay, Sumberjaya

Interpreting flow persistence on basis of flow pathways:

• Flow persistence of overland flow ~ 0.0

• ,, interflow (soil quick flow) ~ 0.5

• ,, groundwater flow ~ 0.95

ConclusionsThree quantitative indicators are now available for

further testing:1) Flow persistence – day-to-day predictability of

riverflow; 1 = perfectly bufferred, 0 = no buffering at all; index can be decomposed into flow path contributions

2) Buffer indicator as above-average discharge per unit above-average rainfall: seasonal or yearly indicator

3) CumRain versus CumRiverflow transition points for sponge saturation effects and timing of buffer saturation