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| Titel |
Regionalisation for lake level simulation – the case of Lake Tana in the Upper Blue Nile, Ethiopia |
| VerfasserIn |
T. H. M. Rientjes, B. U. J. Perera, A. T. Haile, P. Reggiani, L. P. Muthuwatta |
| 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 ; 15, no. 4 ; Nr. 15, no. 4 (2011-04-08), S.1167-1183 |
| Datensatznummer |
250012744
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| Publikation (Nr.) |
 copernicus.org/hess-15-1167-2011.pdf |
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| Zusammenfassung |
In this study lake levels of Lake Tana are simulated at daily time step by
solving the water balance for all inflow and outflow processes. Since nearly
62% of the Lake Tana basin area is ungauged a regionalisation procedure
is applied to estimate lake inflows from ungauged catchments. The procedure
combines automated multi-objective calibration of a simple conceptual model
and multiple regression analyses to establish relations between model
parameters and catchment characteristics.
A relatively small number of studies are presented on Lake Tana's water
balance. In most studies the water balance is solved at monthly time step
and the water balance is simply closed by runoff contributions from ungauged
catchments. Studies partly relied on simple ad-hoc procedures of area comparison
to estimate runoff from ungauged catchments. In this study a regional model
is developed that relies on principles of similarity of catchments
characteristics. For runoff modelling the HBV-96 model is selected while
multi-objective model calibration is by a Monte Carlo procedure. We aim to
assess the closure term of Lake Tana's water balance, to assess model
parameter uncertainty and to evaluate effectiveness of a multi-objective
model calibration approach to make hydrological modeling results more
plausible.
For the gauged catchments, model performance is assessed by the
Nash-Sutcliffe coefficient and Relative Volumetric Error and resulted in
satisfactory to good performance for six, large catchments. The regional
model is validated and indicated satisfactory to good performance in most
cases. Results show that runoff from ungauged catchments is as large as 527 mm
per year for the simulation period and amounts to approximately 30% of
Lake Tana stream inflow. Results of daily lake level simulation over the
simulation period 1994–2003 show a water balance closure term of 85 mm
per year that accounts to 2.7% of the total lake inflow. Lake level
simulations are assessed by Nash Sutcliffe (0.91) and Relative Volume Error
(2.71%) performance measures. |
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