Abstract:
The renewable sources of energy plays the most important role in socio-econom
development in Rwanda that have a favorable topographic condition because of hi
variation of elevation make the country one of the richest nations in terms of hydropow
potential and the study was done on Upper Nyabarongo that is an elongated catchment ar
sloping down from south to north.
The assessment and evaluation of the hydropower potential available in all the sub basi
in the Upper Nyabarongo catchment was completed. Potential head drops were calculat
from a digital elevation model with a 1-arc-second resolution (approximately 30
resolution at equator) where head drops greater or equal to 5 m were selected. The rainf
data used come from eight rainfall gages. The potential hydropower of all streams w
estimated as 67 megawatts using design discharges corresponding to 45th percentile flo
with the hydraulic head. Within the study area there were 8 rainfall gages, one minimu
and maximum temperature gage and one stream flow gages with long-term data recor
To estimate the daily discharges of the reaches are derived from hydrologic and clima
data using HEC-HMS model that divided the catchment into 8sub- basins and 14 riv
reaches was used. Stream reaches, upstream areas, and mean annual rainfall were estimat
using GIS techniques.
The overall simulated stream flows were significantly correlated with the observed flow
with Nash efficiency of 0.905 and volume percentage difference of 2.62 and the accurac
of the flows estimated with the HEC-HMS Model was validated with Nash efficiency o
0.95.The results indicate that the potential hydropower is mostly concentrated near
Muhanga and Ngororero Districts and Sub basins W780 and W580 showed the highest
potential. In addition to the hydropower estimates, potential hydropower estimates with
flow rates with exceedance probabilities of 45 percent, 60 percent, and 95 percent were
made.
Therefore, this study has shown the limitations and potentialities in giving support to th
mid to long term planning of the energy sector in Rwanda.
