Space-time Variation of Hydrological Processes and Water Resources in Rwanda : Focus on the Migina Catchment

This book presents the hydrological research carried out in the Migina catchment (260 km²), Southern Rwanda. The main objective of the research is to explore the hydrological trends and climate linkages for catchments in Rwanda (26,338 km²), and to contribute to the understanding of dominant hydrological process interactions. The research consists of trend analysis and hydrometric data and modern tracer methods for hydrograph separation and semi-distributed conceptual hydrological modelling for assessing the spatio-temporal variation of water resources in the Migina catchment. The hydrological model results are compared with tracer methods in terms of the runoff components.

Presenting the hydrological research carried out in the Migina catchment (260 km²), Southern Rwanda with the objective to explore the hydrological trends and climate linkages for catchments in Rwanda (26,338 km²), and to contribute to the understanding of dominant hydrological process interactions. Different Hydro-meteorological instrumentations have been installed for several months in the Migina catchment and measurements have been carried out. The trend analysis is based on Mann-Kendall (MK) test and Pettitt test on times series data varying from 30 to 56 years before 2000. The hydrometric data and modern tracer methods is used for hydrograph separation and show that subsurface runoff is dominating the total discharge even during rainy seasons at Cyihene-Kansi and Migina sub-catchments, respectively. Further, a semi-distributed conceptual hydrological model HEC-HMS is applied for assessing the spatio-temporal variation of water resources in the Migina catchment. The model results are compared with tracer based hydrograph separation results in terms of the runoff components. The model performed reasonably well in simulating the total flow volume, peak flow and timing as well as the portion of direct runoff and baseflow.