| Title: | Sources of unceratinty in climate change impacts on river discharge and groundwater in a headwater catchment of the Upper Nile Basin, Uganda |
| Authors: | Kingston, D.G. and R.G. Taylor |
| Year: | 2010 |
| Journal: | Hydrology and Earth System Sciences |
| Volume (Issue): | 23(6) |
| Pages: | 1297-1308 |
| Article ID: | |
| DOI: | 10.5194/hess-14-1297-2010 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| Broad Application Category: | hydrologic only |
| Primary Application Category: | climate change |
| Secondary Application Category: | hydrologic assessment |
| Watershed Description: | 2098 km^2 Mitano River in southwestern Uganda |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | The changing availability of freshwater resources
is likely to be one of the most important consequences of
projected 21st century climate change for both human and
natural systems. However, substantial uncertainty remains
regarding the precise impacts of climate change on water
resources, due in part due to uncertainty in GCM projections
of climate change. Here we explore the potential impacts
of climate change on freshwater resources in a humid,
tropical catchment (the River Mitano) in the Upper Nile
Basin of Uganda. Uncertainty associated with GCM structure
and climate sensitivity is explored, as well as parameter
specification within hydrological models. These aims are
achieved by running pattern-scaled output from seven GCMs
through a semi-distributed hydrological model of the catchment
(developed using SWAT). Importantly, use of pattern-scaled
GCM output allows investigation of specific thresholds
of global climate change including the purported 2 deg C
threshold of “dangerous” climate change. In-depth analysis
of results based on the HadCM3 GCM climate scenarios
shows that annual river discharge first increases, then declines
with rising global mean air temperature. A coincidental
shift from a bimodal to unimodal discharge regime also
results from a projected reduction in baseflow (groundwater
discharge). Both of these changes occur after a 4 deg C rise
in global mean air temperature. These results are, however,
highly GCM dependent, in both the magnitude and direction
of change. This dependence stems primarily from projected
differences in GCM scenario precipitation rather than temperature.
GCM-related uncertainty is far greater than that
associated with climate sensitivity or hydrological model parameterisation. |
| Language: | English |
| Keywords: | |