Climate change impact on water resources and adaptation strategies in the Blue Nile River Basin
Book Chapter
Setegn, SG, Melesse, AM, Rayner, D et al. (2014). Climate change impact on water resources and adaptation strategies in the Blue Nile River Basin
. 9783319027203 389-404. 10.1007/978-3-319-02720-3_20
Setegn, SG, Melesse, AM, Rayner, D et al. (2014). Climate change impact on water resources and adaptation strategies in the Blue Nile River Basin
. 9783319027203 389-404. 10.1007/978-3-319-02720-3_20
We compared projected changes in precipitation and temperature across global climate models (GCMs) for two future periods to get an indication of the consistency of the projected changes in the Lake Tana subbasin of the Blue Nile basin. We found that the models projected temperature increases of around 2∈°C to 5∈°C for 2080-2100, depending on the model and emission scenario. The interquartile ranges of the projected temperature increases for 2070-2100 for the three emission scenarios show 2.0-4.4∈°C in the wet season and 2.2-4.9∈°C in the dry season. The ensemble of GCMs we examined includes models that project increases and decreases in seasonal precipitation. The interquartile ranges of the projected rainfall changes for 2070-2100 for the three emission scenarios show -∈13 to +∈12∈% in the wet season and -∈14 to +∈16∈% in the dry season. The study investigated how changes in temperature and precipitation might translate into changes in streamflows and other hydrological components using downscaled outputs from different climate models. The direction of streamflow changes followed the direction of changes in rainfall. The responses of evapotranspiration, soil moisture (SW), and groundwater (GW) were also examined, and it was found that changes in GW flow may be a significant component of the changes in streamflow. The effect of climate change has the potential to cause agricultural drought, unless there is ample water available for irrigation. However, a reduction in rainfall may cause reduced GW recharge, which would significantly reduce its contribution to streamflow. Lake Tana is highly sensitive to variations in rainfall, as well as in river inflows and evaporation.
