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2nd International Conference on the Status and Future of the
World‘s Large Rivers
21-25 July, 2014 Manaus, Amazon, Brazil
Teodoru C.R., Borges, A.V., Nyoni, F., Nyambe, I., Darchambeau, F., & Bouillon, S.
Teodoru, C.R.1,
Borges, A.V.2, Nyoni, F.3, Nyambe, I.(3), Darchambeau F.2 & Bouillon, S.1
1 K.U. Leuven, Department of Earth and Environmental Sciences, Leuven, Belgium
2 University of Liège, Chemical Oceanography Unit, Liège, Belgium
3 University of Zambia, IWRM Centre, Lusaka, Zambia
Temporal variability and spatial distribution of suspended matter and organic C pool
in the Zambezi River system
AFRIVAL Project (African River Basins)http://ees.kuleuven.be/project/afrival/
2nd International Conference on the Status and Future of the
World‘s Large Rivers
21-25 July, 2014 Manaus, Amazon, Brazil
Teodoru C.R., Borges, A.V., Nyoni, F., Nyambe, I., Darchambeau, F., & Bouillon, S.
The Zambezi River Basin – general characteristics
• 4th largest in Africa and the largest flowing in to the Indian Ocean (from Africa)
• Total length: > 3000 km; Drainage basin: ~ 1.4 x 106 km2 (shared by 8 countries)
• Main tributaries: Kabompo (270 m3/s), Luangina (65 m3/s), Kwando (53 m3/s),
Gwayi (85 m3/s), Kafue (370 m3/s), Luangwa (520 m3/s), Shire (115 m3/s)
• 2 main reservoirs: Kariba (5600 km2; 180 km3), and Cahora Bassa (2600 km2; 50
km3)
Kariba Res.
Cahora Bassa Res.
Victoria Falls Zambezi Delta
Zambezi source
BarotseFloodplains
Foto: Patrick
Wagner
LUKANGA
2nd International Conference on the Status and Future of the
World‘s Large Rivers
21-25 July, 2014 Manaus, Amazon, Brazil
Teodoru C.R., Borges, A.V., Nyoni, F., Nyambe, I., Darchambeau, F., & Bouillon, S.
The Zambezi River Basin – climate and rainfall
• Climate is classified as humid subtropical or tropical wet and dry
• Annual rainfall varies with latitude: 1400 mm in N to 400-500 mm in S (mean
average rainfall for entire basin: 940 mm)
• Two seasons:
1. Wet season (Oct/Nov – Apr) corresponding to summer, with 95% of annual rainfall
2. Dry season (May – Sep/Oct), corresponding to winter, with 5% of annual rainfall
• Temperature across basin varies with elevation and, and less with latitude
• Mean monthly t°: 13°C for higher elevation in S to 23°C in E (July); and 23°C -
31°C (Oct)
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
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Apr
May
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Oct
Nov
Dec
Jan
Feb
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Apr
May
Jun
Jul
0
50
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250
Dry Season
May-Sep
(40 mm)
Month
ly P
recip
ita
tion [
mm
]
Wet Season
Oct-Apr
(900 mm)
2nd International Conference on the Status and Future of the
World‘s Large Rivers
21-25 July, 2014 Manaus, Amazon, Brazil
Teodoru C.R., Borges, A.V., Nyoni, F., Nyambe, I., Darchambeau, F., & Bouillon, S.
The Zambezi River Basin – hydrological cycle
• Driven by seasonality in rainfall patterns, hydrological cycle of the basin has a
bimodal distribution with a single main peak flood (max. Q: Apr/May) and min.
flow in Oct/Nov
• Due to regional rainfall distribution, northern tributaries contribute much more
water than southern ones
• Average annual discharge at Zambezi Delta: 3500-4000 m3 s-1
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0
1000
2000
3000
4000
5000
6000
7000
8000
2010-2011
Wet Season
Dis
cha
rge
[m
3 s
-1]
Date [mm/dd/yy]
Victoria Falls
Kariba DamDry Season
2011-2012 2012-2013
2nd International Conference on the Status and Future of the
World‘s Large Rivers
21-25 July, 2014 Manaus, Amazon, Brazil
Teodoru C.R., Borges, A.V., Nyoni, F., Nyambe, I., Darchambeau, F., & Bouillon, S.
Sampling Strategy
• 3 campaigns: Wet (Feb-Apr) 2012, Wet (Jan-Apr) 2013, Dry (Oct-Dec) 2013
• 56 sites: 26 along Zambezi (Kariba & CB Res.), and 30 on tributaries (ITT Res.)
• 2 monitoring stations (Feb 2012 – Dec 2013):
ZBZ.11 ~ 5 km upstream the confluence with Kafue
KAF.10 ~ 6 km upstream the confluence with Zambezi
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/2013
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/2014
0
1000
2000
3000
4000
5000
6000
7000
8000
2010-2011
Wet Season
Dis
cha
rge [
m3 s
-1]
Date [mm/dd/yy]
Victoria Falls
Kariba DamDry Season
biweekly monitoring: Zambezi and Kafue
Wet 2012
Dry
20
13
2011-2012 2012-2013
Wet 2013
2nd International Conference on the Status and Future of the
World‘s Large Rivers
21-25 July, 2014 Manaus, Amazon, Brazil
Teodoru C.R., Borges, A.V., Nyoni, F., Nyambe, I., Darchambeau, F., & Bouillon, S.
Measured parameters
• Physico-chemical: pH, O2, t°, conductivity, Total Alkalinity
• Total Suspended Matter (TSM) and sediment characterization
• Concentration and stable isotope (δ13C and δ15N) composition
of POC, PN, DOC, DIC
• Aquatic metabolism: community respiration, primary production
• GHG (CO2, CH4, N2O) concentrations and fluxes
Headspace Technique Membrane Equilibrator Floating chamber
In-situ CO2 concentrations Fluxes
2nd International Conference on the Status and Future of the
World‘s Large Rivers
21-25 July, 2014 Manaus, Amazon, Brazil
Teodoru C.R., Borges, A.V., Nyoni, F., Nyambe, I., Darchambeau, F., & Bouillon, S.
TSM – spatio-temporal dynamics
0 200 400 600 800 1000 1200 1400 1600
1
10
100
1000
Lukanga Swamps
ITT Res. (2012 wet)
ITT Res. (2013 wet)
ITT Res. (2013 dry)
TS
M -
Ka
fue
Riv
er
[mg L
-1]
Distance from source [km]
Kafue (2012 wet) Kafue (2013 wet)
Kafue (2013 dry)
Kafue Flats
0 500 1000 1500 2000 2500 3000
1
10
100
1000
Barotse Floodplains
C.B. Res. (2012 wet)
C.B. Res. (2013 wet)
Kariba Res. (2012 wet)
Kariba Res. (2013 wet)
Kariba Res. (2013 dry)
ZBZ (2012 wet)
ZBZ (2013 wet) ZBZ (2013 dry)
TS
M -
Zam
be
zi R
iver
[mg L
-1]
Distance from source [km]
Shire River
(6-11 mg L-1)
Zambezi River Kafue River
Wet 2012 Wet 2013 Dry 2013 D Wet 2012 Wet 2013 Dry 2013
1
10
100
1000
Zambezi Kafue
p>0.093
p>0.293
TS
M [
mg L
-1]
p>0.109
p>0.912
NO interannual variability
NO distinct seasonality
2nd International Conference on the Status and Future of the
World‘s Large Rivers
21-25 July, 2014 Manaus, Amazon, Brazil
Teodoru C.R., Borges, A.V., Nyoni, F., Nyambe, I., Darchambeau, F., & Bouillon, S.
TSM – spatio-temporal dynamics
0 200 400 600 800 1000 1200 1400 1600
1
10
100
1000
Lukanga Swamps
ITT Res. (2012 wet)
ITT Res. (2013 wet)
ITT Res. (2013 dry)
TS
M -
Ka
fue
Riv
er
[mg L
-1]
Distance from source [km]
Kafue (2012 wet) Kafue (2013 wet)
Kafue (2013 dry)
Kafue Flats
0 500 1000 1500 2000 2500 3000
1
10
100
1000
Barotse Floodplains
C.B. Res. (2012 wet)
C.B. Res. (2013 wet)
Kariba Res. (2012 wet)
Kariba Res. (2013 wet)
Kariba Res. (2013 dry)
ZBZ (2012 wet)
ZBZ (2013 wet) ZBZ (2013 dry)
TS
M -
Zam
be
zi R
iver
[mg L
-1]
Distance from source [km]
Shire River
(6-11 mg L-1)
Zambezi River Kafue River
Zambe
ziKar
iba
Res
.C
.B. R
es.
Kabom
po
Kafue
ITT R
es.
Lung
aLu
angw
aLu
nsem
fwa
Maz
oe
Shire
1
10
100
1000
TS
M r
an
ge
[m
g L
-1]
Wet 2012 Wet 2013 Dry 2013 D Wet 2012 Wet 2013 Dry 2013
1
10
100
1000
Zambezi Kafue
p>0.093
p>0.293
TS
M [
mg L
-1]
p>0.109
p>0.912
NO interannual variability
NO distinct seasonality
2nd International Conference on the Status and Future of the
World‘s Large Rivers
21-25 July, 2014 Manaus, Amazon, Brazil
Teodoru C.R., Borges, A.V., Nyoni, F., Nyambe, I., Darchambeau, F., & Bouillon, S.
POC, PN, δ13CPOC, C:N ratio
1 10 100 10000.1
1
10
100
% P
N [
%]
TSM [mg L-1]
1 10 100 10000.1
1
10
100
ITT Res.
Lunga
Luangwa
Lunsemfwa
Mazoe
Shire
Zambezi
Kariba Res.
C.B. Res.
Kabompo
Kafue
% P
OC
[%
]
-33 -32 -31 -30 -29 -28 -27 -26 -25 -24 -23 -22 -21 -20 -19 -180.1
1
10
100
Lunga
Luangwa
Lunsemfwa
Mazoe
Shire
Zambezi
Kariba Res.
C.B. Res
Kabompo
Kafue
ITT Res.
Perc
ent
PO
C [
%]
δ13
CPOC
[‰]
-33 -32 -31 -30 -29 -28 -27 -26 -25 -24 -23 -22 -21 -20 -19 -182
4
6
8
10
12
14
16
18
20
22 Kafue
ITT Res. Lunga
Luangwa
Lunsemfwa
Mazoe
Shire
Zambezi Kariba res.
C.B. Res. Kabompo
Mo
lar
C:N
ratio
δ13
CPOC
[‰]
POC - predominantly terrestrial (C3) origin:
Luangwa – more towards C4 soil C;
Reservoirs – fraction from phytoplankton
production
2nd International Conference on the Status and Future of the
World‘s Large Rivers
21-25 July, 2014 Manaus, Amazon, Brazil
Teodoru C.R., Borges, A.V., Nyoni, F., Nyambe, I., Darchambeau, F., & Bouillon, S.
DOC– spatio-temporal dynamics
Zambezi River Kafue River
0 500 1000 1500 2000 2500 30000.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
Shire River
C.B. Res. (2012 wet) C.B. Res. (2013 wet)
Kariba Res. (2012 wet)
Kariba Res. (2013 wet)
Kariba res. (2013 dry)
ZBZ (2012 wet)
ZBZ (2013 wet)
ZBZ (2013 dry)
DO
C -
Za
mb
ezi R
ive
r [m
g L
-1]
Distance from source [km]
Barotse Floodplains
0 200 400 600 800 1000 1200 1400 16000.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
Kafue Flats
Lukanga Swamps
ITT Res. (2012 wet)
ITT Res. (2013 wet) ITT Res. (2013 dry)
DO
C -
Kafu
e R
iver
[mg
L-1]
Distance from source [km]
Kafue (2012 wet) Kafue (2013 wet)
Kafue (2013 dry)
Zambe
ziKar
iba
Res
.C
.B. R
es.
Kabom
po
Kafue
I.T.T
. Res
.
Lung
aLu
angw
aLu
nsem
fwa
Maz
oe
Shire
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
Ran
ge
DO
C [
mg L
-1]
Wet 2012 Wet 2013 Dry 2013 G1 Wet 2012 Wet 2013 Dry 20130.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
DO
C [
mg
L-1]
Zambezi Kafue
p>0.002
p>0.018
p>0.258
p>0.019
Distinct seasonality
2nd International Conference on the Status and Future of the
World‘s Large Rivers
21-25 July, 2014 Manaus, Amazon, Brazil
Teodoru C.R., Borges, A.V., Nyoni, F., Nyambe, I., Darchambeau, F., & Bouillon, S.
DOC isotopic signature (δ13CDOC), and Age (∆14CPOC, ∆14CDOC)
-32 -30 -28 -26 -24 -22 -20 -18
-32
-30
-28
-26
-24
-22
-20
-18
Lunga
Luangwa
Lunsemfwa
Mazoe
Shire
Zambezi
Kariba Res.
C.B. Res.
Kabompo
Kafue
I.T.T. Res.
δ1
3C
DO
C [
‰]
δ13
CPOC
[‰]
1:1
0 1000 2000 3000-20
-10
0
10
20
30
40
50
60
70
80
Distance from source [km]
∆14C
PO
C [
‰]
20
30
40
50
60
70
80
90
100
110
120 Zambezi (∆
14C
DOC)
Reservoirs (∆14
CDOC
)
Tributaries (∆14
CDOC
)
Zambezi (∆14
CPOC
)
Reservoirs (∆14
CPOC
)
Tributaries (∆14
CPOC
)
∆1
4C
DO
C [
‰]
0 500 1000 1500 2000 2500 3000
-28
-26
-24
-22
-20
-18
1.0 2.0 3.0 4.0 5.0 6.0
-28
-26
-24
-22
-20
-18
Distance from source [km]
δ13C
DO
C [
‰]
Zambezi
Reservoirs
δ1
3C
DO
C [
‰]
DOC [mg L-1]
r2 = 0.5
DOC – mostly C3 origin with minimal
in-stream autochthonous production
δ13CDOC: δ13POC – decupling
between DOC and POC sources
∆14C – modern nature of riverine
organic C pool
2nd International Conference on the Status and Future of the
World‘s Large Rivers
21-25 July, 2014 Manaus, Amazon, Brazil
Teodoru C.R., Borges, A.V., Nyoni, F., Nyambe, I., Darchambeau, F., & Bouillon, S.
Carbon Mass Balance
Area Q TSM POC DOC DIC CO2 CH4 C Yield GHG C Deposition C Export
[km2] [m3 s-1] [kt C yr-1]
Zambezi at Delta 11445 3779 9558 306 263 3672 2681 46.1 7163 2727 196 4240
Kafue at M.S. 658 314 196 8 45 205 459 4.6 738 464 16 258
Zambezi at M.S. 6403 1237 282 34 99 398 385 20.2 1042 391 120 531
Zambezi + Kafue =>
Zambezi & Kafue =>at monitoring stations (M.S.)
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