Transcript Tropical forests and water flows: from small watersheds to the pantropics “Functional Value of Biodiversity” Project with support from World Bank Netherlands Partnership Program “FVOB”

Tropical forests and water flows:
from small watersheds to the pantropics
“Functional Value of Biodiversity” Project
with support from
World Bank Netherlands Partnership Program
“FVOB” is a component of ASB’s crosscutting assessment
“Forest and Agroecosystem Tradeoffs in the Humid Tropics”
a sub-global component of
the Millennium Ecosystem Assessment (MA)
Team members
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Jeffrey Richey, UW
Ellen Douglas & Charles Vörösmarty, UNH
Kate Sebastian & Stanley
Wood, IFPRI
n
Kenneth Chomitz, DECRG
Meine van Noordwijk & Thomas Tomich,
ICRAF
• plus other team members not here today
• plus contributions of others not directly involved
in this project
Overview
•
•
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Introduction
Integrated assessment of real concerns
Framework
Micro scale
Meso scale
Pantropic scale
Conclusions
The ASB Matrix
M e ta L a n d U s e s
G lo b a l
E n viro n m e n ta l
C o n c e rn s
A g ro n o m ic
S u s ta in a b ility
S m a llh o ld e rs ’
S o c io e c o n o m ic
C o n c e rn s
P o lic y &
In s titu tio n a l
Is s u e s
N a tu ra l F o re s t
F o re s t E x tra c tio n
C o m p le x , M u ltis tra ta
A g ro fo re s try
S y s te m s
S im p le T re e c ro p
S y s te m s
C ro p /F a llow S y s te m s
C o n tin u o u s A n n u a l
C ro p p in g S y s te m s
G ra s s la n d s /P a s tu re
TP Tomich
ASB Matrix for the Forest
Margins of Sumatra
Land use
D e s c rip tio n
S cale of
operation /
evaluation
G lo b a l
e n v iro n m e n t
C arbon
sequestra
-tion
B iodiversity
T im e
averaged
(M T /ha/yr)
A boveG round
A g ro n o m ic
s u s ta in a b ility
P lot-level production
sustainability
O verall
rating
species /
m odi ratio
M ain
sustainability
issues (1)
N a tio n a l
p o lic ym a k e rs ’
c o n c e rn s
A d o p ta b ility b y s m a llh o ld e rs
P otential
profitability
E m ploym ent
P roduction
incentives
H ousehold food
security
R eturns to land
T im e averaged
labor input
(days/ha/yr)
R eturns to
Labor
(R p / day) at
private prices
F ood
entitlem ent
via:
(R p 000 / ha) at
social prices
Institutional & policy
issues
M arket
im perfections
O ther
institutional
problem s
(2)
(3)
N a tu ra l fo re s t
2 5 h a fra g m e n t /
1 ha
254
2.78
1
0
0
0
n .a.
C o m m u n ityb a s e d fo re s t
m anagem ent
3 5 ,0 0 0 h a
co m m o n fo re st
/ 1 ha
176
2.74
1
9.4 to 18
0.2 to 0.4
11,000 to
12,000
o w n p ro d n
&
exchange
C o m m e rc ia l
lo g g in g
3 5 ,0 0 0 h a
co n ce ssio n / 1 h a
150
2.84
0.5
C
(32) to 1,500
5
(20,000) to
(4,400)
w ages
R ubber
a g ro fo re s t
R u b b er
a g ro fo rest w /
1 -5 h a p lo ts / 1
ha
116
2.08
0.5
C
73
111
4,000
exchange
1 -5 h a p lo ts / 1
ha
103
0 .5
C ,K ,W ,P
2 3 0 to 3 ,6 0 0
150
3 ,9 0 0 to 6 ,9 0 0
exchange
I, k
N, P, b, c
R u b b er
m o n o cu ltu re
1 -5 h a p lo ts / 1
ha
97
1 .8 6
0 .5
C ,W ,P
(9 9 0 )
133
1800
exchange
I, k
N, P, b, c
O il p a lm
m o n o c u ltu re
3 5 ,0 0 0 h a e sta te
/ 1 ha
91
1.18
0.5
C ,F ert
2500
108
8,600
w ages
I, o , K
U p la n d ric e /
b u s h fa llo w
ro ta tio n
1 -2 h a p lo ts / 1
ha
74
1.39
0.5
F ert,P
(180) to 53
15 to 25
2,700 to 3,300
own
p ro d u c tio n
N , R , e, P ,
B, c
n, P, c
C o n tin u o u s
cassava
d e g ra d in g to
Im p e ra ta
1 -2 h a p lo ts
w ith in se ttle m e n t
p ro je ct / 1 h a
39
1.1
0
C ,F ert,W
(700) to (1,700)
63 to 73
1,800 to 3,300
own
p ro d ’n &
exchange
o, K
n, E, p, c
o
N, R, P, C
O, K
N, R, E, P,
B, C
P, b, c
clo n a l p la n tin g
m a teria l
TP Tomich
Strong coincidence of watershed
functions, biodiversity and
poverty alleviation agendas
Or
People
People
Little overlap, separate attention
for watershed_functions*poverty
and biodiversity* poverty
Tropical Forest Biomes
River Basins Containing Tropical Forest Biomes
Population density within the pan-tropic basins
Share of pre-industrial land cover converted by 1992/93
(Contemporary)
Conversion is the sum of agricultural (cropland and
pasture – rainfed & irrigated) and urban land cover
contained in the contemporary land cover.
Table 1. Measurability of land use impacts by basin size (Kiersch and
Tognetti, 2002) x = Measurable impact; – = No measurable impact
___________________________________________________
Impact Type Basin size [km2]
0.1
1
10
102
103
104
105
_____________________________________________________________________________________
Thermal regime 1.Is there
x simply
x a lack
–
ofx data here?
Pathogens
x
x
on
Average flow 2. Arex LU impacts
x
x
this group
Peak flow
x of xfunctions
x
really
to x
Base flow
x restricted
x
‘small’ areas?
Groundwater
3. Dox we understand
recharge
x
x
Organic matter why this
x could
x be so?
x
Sediment load 4. What
x doesxit meanx
for upland-lowland
Nutrients
x
x
x
interactions?
Salinity
x
x
x
Pesticides
x
x
x
Heavy metals
x
x
x
–
–
x
x
x
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
x
x
x
x
x
x
x
–
–
–
x
x
x
x
–
–
–
–
x
x
x
–
–
–
–
x
x
x
Site characteristics
Watershed
functions
Relevant
for
• Rainfall
• Land
form
• Soil type
• Rooting
depth
(natural
1. Transmit water
2. Buffer peak rain
events
3. Release gradually
4. Maintain quality
5. Reduce mass
wasting
• Downstream
water users,
• esp. living in
floodplains &
river beds,
• w.o. storage
• or purification
vegetation)
cloud
interception
water
What matters most in a ‘forest’: canopy
evaporation
rainfall
transpiration
surface
evaporation
the trees
through-fall
the landscape
surface
run-on
stem-flow
Stream:
surface infiltration
quickrecharge
run-off
flow
lateral
outflow
{
base
flow
?
percolation
the soil
uptake
subsurface
lateral
inflow
Looking at the water balance in summary terms:
Precipitation = P
River flow = Q
Qquick
Evapotranspiration = E
Qslow
Eveg
Esoil
Eirr Einterc
and understanding it from a summation of ‘event’-level processes:
precipitation
Signal modification
along river
interception
Qquick
infiltration
Qslow
Einterc
Esoil + Eveg
Energylimited
Epotential
We need ‘models’ to keep track of the various interaction terms….
Af
Fo
te
re
rc
st
on
In
ve
it i
rs
al
io
d
n
eg
Se
ra
rio
da
us
t io
de
n
g
Af
ra
da
te
rr
tio
ef
n
or
es
Lo
ta
tio
ng
n
te
rm
re
ha
b
Fraction ofr annual rainfall
Hydrological null-model
100%
80%
60%
EvapTrans
Quick flow
Slow flows
40%
20%
0%
Stage in land use change
Nested, Overlapping Hydrologic Model Capabilities
Space
(km2)
100,000
WBM
10,000
VIC
1,000
100
10
GENRIVER,
DHSVM
WANULCAS
FALLOW
1
Time
Hours
Days
Weeks
Months
Years
90
D a ily ra in fa ll (s ta tio n le v e l), m m
Daily rainfall (station level), mm
180
80
160
70
140
Rainfall
60
120
50
100
40
30
20
10
0
600
0
100
200
300
80
60
40
20
0
120
0
100
Day of year
200
300
Day of year
100
River flow
River debit, m3 s-1
s
-1
500
R iv e r d e b it, m
3
400
300
200
80
60
40
100
20
0
0
0
50
100
150
200
250
300
Day of year
Mae Chaem (Thailand),
1.5 m rainfall, 10 persons km-2
350
0
50
100
150
200
250
300
350
Day of year
Way Besai (Indonesia),
2.5 m rainfall, 100 persons km-2
Mae Chaem
0.8
0.6
12
R ive r flo w
0.4
R a infa ll
River flow, mm day-1
1 - e x c e e d a n c e p ro b a b ility
1.0
0.2
0.0
0
20
40
60
80
100
m m d a y -1
1 - exceed an ce p ro b ab ility
1 .0
0 .9
0 .8
4
2
R a infa ll
0 .2
0 .1
0 .0
0 .1
20
40
60
Rainfall, mm day-1
R ive r flo w
0 .4
0 .0 1
6
0
0 .6
0 .3
8
0
0 .7
0 .5
10
1
m m d a y-1
10
100
80
100
Basic properties: transforming rainfall signal to
stream and riverflow signals
Exceedance
probability
0
Area under the curve:
rainfall
stream
river
1
mm day-1
Rainfall = ET + River +
+storage
Importance declines
with time of
consideration
Sorted river flow, mm/day
Points indicating ‘breakdown’ of normal buffering at extreme events
Slope ~ 1 – buffering indicator
River flow on
rainless days
Sorted rainfall, mm/day
Way Besai Rain and Riverflow exceedance for two
types of rain
140
R iverflo w exeed an ce, m m d ay -1
R iverflo w exeed an ce, m m d a y -1
H o m o g e n o u s R a in
P a tch y R a in
140
120
100
80
60
40
20
120
100
80
60
40
20
0
0
0
30
60
90
R a in e x e e d a n ce , m m d a y -1
A llF ores t
M ix edLU
A llG ras s
120
150
0
30
60
90
120
R a in e x e e d a n ce , m m d a y -1
A llF ores t
M ix edLU
A llG ras s
150
c o ffe e
Up land
S un
c ro p s &
c o ffe e
fallo w
40
20
F o re s t
25.0
20.0
15.0
10.0
5.0
1980
1990
2000
Period
1
2
150
100
O th er
50
F orest
S h 1975-1998
ad e coffee
50
1980
1990
1975-1981
1982-1988
1990-1998
2 0 0 0 22002150?
100
T im
e , y e a r 150
Rainfall, mm day -1
3
Plot-level buffering gets
lost…. But the internal
floodplain replaces its role
Tentative interpretation…..
s c e nario
1970
0.0
0
T im e , y e a r
c hang e
0
0
1970
m axim um
200
T o ta l C s to c k , M g /h a
S had e
80
60
30.0
S e ttle m e n ts & p o n d s
P a d d y ric e
River flow, mm day -1
P e rc e n ta g e la n d c o v e r
100
Measurement
point
200
Macropore distribution
1.5 m
Forest
Coffee 7 yr
Coffee 1 yr
Coffee 10 yr
Coffee 3 yr
Forest baseline
1
1
W
2
B
4
0
3
Progressive land use change
“Geospatially-explicit process-based models
provide fundamental new insight”
MEKONG
VIC (Variable Infiltration Capacity)
Meso/Macroscale Landscape/Hydrologic Model
(Daily, 1-10 km)
MAE CHAEM
DHSVM (Distributed Hydrology Soil
Vegetation Model)
Micro/Mesoscale Landscape/Hydrologic Model
(4h, 150m)
Mae Chaem: SCENARIOS OF HYDROLOGIC RESPONSES
Veg89
(7/9/99)
1500
Veg2000irr
Crop
Crops
(7/9/99)
ET
Crop Bad Soil
1000
500
SM
0
N95
N96
N97
N98
N99
N00
Ban Chot
Yanothon
Rasi Salai
Mun
Ubon
MUN RIVER Scenarios
Obs
1500
Model
Ban Chot
5000
1200
4000
900
3000
600
2000
300
1000
0
80
85
90
95
00
5000
Rasi Salai
0
8000
3000
6000
2000
4000
1000
2000
80
85
90
95
00
Yasothon
80
85
90
95
10000
4000
0
All Forest
No Forest
0
00
Ubon
80
85
90
95
00
MEKONG: “Daily/10 km Resolution”
15000
Chiang Saen
12000
9000
6000
3000
0
80
85
90
95
00
60000
Stung Treng
Mun
45000
30000
15000
0
80
85
90
95
00
Precipitation
Discharge Hydrographs
Ipswich R. Runoff Validation 1993-1995
Runoff (mm/d)
Runoff (mm/d)
20
15
predicted
10
observed
5
0
-5
-10
-15
-20
1/1/93
7/20/93
2/5/94
8/24/94
3/12/95
9/28/95
Date
Evapotranspiration
Lateral Transport
Channel
Topology
WBM/WTM
Runoff
450
O ye b a n d e 1 9 8 8 (d e fo re s ta tio n )
300
150
0
0
0 .2
0 .4
0 .6
0 .8
1
F o re s t c o ve r c h a n g e (fra c tio n o f o rig in a l)
450
 B a s in -a v e ra g e d R u n o ff (m m /y r)
C han ge in A nnua l Y ie ld (m m )
O ye b a n d e 1 9 8 8 (a ffo re s ta tio n )
300
150
0
0
20
40
60
F o re s t L o s t (a s % o f o rig in a l a re a )
80
100
Scenario 1
N/A
N/A
Tropical forests and water flows
• Deforestation increases total water supply.
• Reforestation does not cause dry rivers to flow
again.
• Upland deforestation increases risks of lowland
flooding (1-20 year return period).
• Upland deforestation is a small factor in the most
devastating floods.
• Forest degradation produces many possible
trajectories of change in biodiversity and
watershed function – these policy objectives are
not tightly linked and there are a wide range of
options.