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| Titel |
Identification of runoff generation processes using hydrometric and tracer methods in a meso-scale catchment in Rwanda |
| VerfasserIn |
O. Munyaneza, J. Wenninger, S. Uhlenbrook |
| 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 ; 16, no. 7 ; Nr. 16, no. 7 (2012-07-09), S.1991-2004 |
| Datensatznummer |
250013360
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| Publikation (Nr.) |
 copernicus.org/hess-16-1991-2012.pdf |
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| Zusammenfassung |
| Understanding of dominant runoff generation processes in the meso-scale
Migina catchment (257.4 km2) in southern Rwanda was improved using
analysis of hydrometric data and tracer methods. The paper examines the use
of hydrochemical and isotope parameters for separating streamflow into
different runoff components by investigating two flood events which occurred
during the rainy season "Itumba" (March–May) over a period of 2 yr at
two gauging stations. Dissolved silica (SiO2), electrical conductivity
(EC), deuterium (2H), oxygen-18 (18O), major anions (Cl− and
SO2−4) and major cations (Na+, K+, Mg2+ and
Ca2+) were analyzed during the events. 2H, 18O, Cl− and
SiO2 were finally selected to assess the different contributing sources
using mass balance equations and end member mixing analysis for two- and
three-component hydrograph separation models. The results obtained by applying
two-component hydrograph separations using dissolved silica and chloride as
tracers are generally in line with the results of three-component
separations using dissolved silica and deuterium. Subsurface runoff is
dominating the total discharge during flood events. More than 80% of the
discharge was generated by subsurface runoff for both events. This is
supported by observations of shallow groundwater responses in the catchment
(depth 0.2–2 m), which show fast infiltration of rainfall water during
events. Consequently, shallow groundwater contributes to subsurface
stormflow and baseflow generation. This dominance of subsurface
contributions is also in line with the observed low runoff coefficient
values (16.7 and 44.5%) for both events. Groundwater recharge during the
wet seasons leads to a perennial river system. These results are essential
for better water resources planning and management in the region, which is
characterized by very highly competing demands (domestic vs. agricultural
vs. industrial uses). |
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