| dc.description.abstract | Evaluating the impact of climate change on sediment yield has become one of the major
topics in climate research. The purpose of this study was to investigate sediment yield contribution to
lake volume change under changing climatic conditions in the Central Rift Valley Basin. The ensemble
mean of five regional climate models (RCMs) in the coordinated regional climate downscaling
experiment (CORDEX)-Africa was considered for the purpose of this study. The climate variables
(precipitation, minimum and maximum temperatures) in RCMs were bias corrected against observed
data (1985–2016) using linear scaling (LS), power transformation (PT), variance of scaling (VS),
and quantile mapping (QM). Two emission scenarios, the Representative Concentration Pathways,
RCP4.5 and RCP8.5, were considered for the future scenario period (2041–2070). Better results were
obtained when the ensemble values of the bias correction methods were used. Hence, the projected
values of climate variables after bias correction were used in the Soil and Water Assessment Tool
(SWAT) hydrological model to estimate the sediment yield contribution to lake volume change due to
climate change. The results show that the average projected precipitation will decrease by 7.97% and
2.55% under RCP4.5 and RCP8.5, respectively. On average, the maximum temperature will increase
by 1.73 ◦C and 2.36 ◦C under RCP4.5 and RCP8.5, respectively, while the minimum temperature
will increase by 2.16 ◦C and 3.07 ◦C under RCP4.5 and RCP8.5, respectively. The average annual
sediment yield contributions to Lake Ziway were 431.05 ton/km2 and 322.82 ton/km2
for the Meki
and Ketar rivers, respectively, in the historical period (1985–2010). The study also reveals that the
annual sediment yield that was estimated for the Meki River was 323 ton/km2 and 382 ton/km2
under RCP4.5 and under RCP8.5, respectively. The sediment estimations for the Ketar River were
157 ton/km2 and 211 ton/km2 under RCP4.5 under RCP8.5, respectively. This will decrease the rate
of volume change in Lake Ziway by 38% under RCP4.5 and by 23% under RCP8.5. The results show
that the life expectancy of the lake is likely to increase under climate change scenarios. This will
help water resources managers make informed decisions regarding the planning, management, and
mitigation of the river basins. | en_US |
