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| Titel |
The potential for remote sensing and hydrologic modelling to assess the spatio-temporal dynamics of ponds in the Ferlo Region (Senegal) |
| VerfasserIn |
V. Soti, C. Puech, D. Seen, A. Bertran, C. Vignolles, B. Mondet, N. Dessay, A. Tran |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 14, no. 8 ; Nr. 14, no. 8 (2010-08-04), S.1449-1464 |
| Datensatznummer |
250012392
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| Publikation (Nr.) |
 copernicus.org/hess-14-1449-2010.pdf |
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| Zusammenfassung |
| In the Ferlo Region in Senegal, livestock depend on temporary ponds for
water but are exposed to the Rift Valley Fever (RVF), a disease transmitted
to herds by mosquitoes which develop in these ponds. Mosquito abundance is
related to the emptying and filling phases of the ponds, and in order to
study the epidemiology of RVF, pond modelling is required. In the context of
a data scarce region, a simple hydrologic model which makes use of remote
sensing data was developed to simulate pond water dynamics from daily
rainfall. Two sets of ponds were considered: those located in the main
stream of the Ferlo Valley whose hydrological dynamics are essentially due
to runoff, and the ponds located outside, which are smaller and whose
filling mechanisms are mainly due to direct rainfall. Separate calibrations
and validations were made for each set of ponds. Calibration was performed
from daily field data (rainfall, water level) collected during the 2001 and
2002 rainy seasons and from three different sources of remote sensing data:
1) very high spatial resolution optical satellite images to access pond
location and surface area at given dates, 2) Advanced Spaceborne Thermal
Emission and Reflection Radiometer (ASTER) Digital Elevation Model (DEM)
data to estimate pond catchment area and 3) Tropical Rainfall Measuring
Mission (TRMM) data for rainfall estimates. The model was applied to all
ponds of the study area, the results were validated and a sensitivity
analysis was performed. Water height simulations using gauge rainfall as
input were compared to water level measurements from four ponds and Nash
coefficients >0.7 were obtained. Comparison with simulations using TRMM
rainfall data gave mixed results, with poor water height simulations for the
year 2001 and good estimations for the year 2002. A pond map derived from a
Quickbird satellite image was used to assess model accuracy for simulating
pond water areas for all the ponds of the study area. The validation showed
that modelled water areas were mostly underestimated but significantly
correlated, particularly for the larger ponds. The results of the
sensitivity analysis showed that parameters relative to pond shape and
catchment area estimation have less effects on model simulation than
parameters relative to soil properties (rainfall threshold causing runoff in
dry soils and the coefficient expressing soil moisture decrease with time)
or the water loss coefficient. Overall, our results demonstrate the
possibility of using a simple hydrologic model with remote sensing data to
track pond water heights and water areas in a homogeneous arid area. |
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