SWOT mission,

expectation for Tropical hydrology

Stéphane CALMANT & Frédérique SEYLER

Columbus, Ohio, 15-17 Sept 2008

Tropical basins: large (transboundary) braided rivers, changing beds with floodplains and wetlands

In practice, impossible to monitor by usual meansSWOT: catch every water body

1984 1991

1993

0 7 km

SWOT: full coverage mapping of changes in river course

Rivers change course with time…

Low waters

High waters

SWOT: inundated surfaces

Floodplain under forestHuge volume xLow velocity River discharge

2 km

Bonnet, M.P, et al. Floodplain hydrology in an Amazon floodplain lake (Lago Grande de Curuaí) Journal of Hydrology

Flood plain dynamics

44,5

55,5

66,5

77,5

88,5

99,510

10,511

11,5

0 10 20 30 40 50

varzea

mainstream

4

5

6

7

8

9

10

11

12

0 0,5 1 1,5 2 2,5

01/10/2005

18/06/2005

05/03/2005

19/11/2004

Flood peak

Flood fall

Flood increase

Low water

V MS

V= Varzea

MS= Main Stream

Floodplain vs main stem

Drawbacks of

conventional nadir altimetry

ENVISAT :hookingFor small rivers

SWOT: direct measurements

Leakage/hooking over temporarily islets

SWOT: no off-nadir ranges ?

025050075050

75

100

125

150

Distance from outlet (km)

Geo

id a

ltit

ud

of

zero

flo

w (

m)

Profile from national chart

Profile by sat altimetry

Caqueta River, Colombia

SWOT: High resolution of river altitude profile

FARCs Guerilla

VB

2.5 5.0 7.5 10.0

2490

4490

6490

8490

10490

H-z (m )

Dis

char

ge

(m3/

s)

Stage-discharge relationship: rating curve at virtual gauges

Leon, J.G., et al. Preliminary estimations of discharges in the Rio Negro basin by the flow routing model proGUM using altimetricspatial data. In revision

SWOT: will improve the time and space sampling frequency to input in the modelling schemes

Drawbacks of Gauges:

SWOT will provide Complementary information

Data of in situ gauges in international databases(exp Global Runoff Data Center)

Global Runoff Data Center

Date de fin des mesures●<1980●1980-1984●1985-1990●1990-1994●1995-2000●2000-2004●<2004

1900 2007

Number of active stations

1980

NEED FOR A RAPIDE, UNRESTRICTED DISTRIBUTION OF THE SWOT DATA

Which height variations?

Gauge is local

SWOT: cross bed slope variations

ANA: Hydrologic network optimization

CNPq –UFAM: Sediment transport models

CNPq – UnB: Floodplain processes and models

ELECTRONORTE: Balbina dam

CPRM : Extreme events management and prevision, underground water quality, fluvial geodynamics

Long Term

AMESD (African Monitoring of the Environment for Sustainable Development ): Congo-Oubangui-Sangha Basin management

Future:

ACTO - FFEM : Integrated and sustainable water management - AGIRE

Madeira dams project

SWOT will provide a full detection of the –now unmonitored- extent and level of each body in the complex river-wetland-inundated areas systems that are characteristic of tropical basins, without harming the temporal sampling, contrarily to conventional nadir altimetry.