| Title: | Land use and climate change impacts on the hydrology of the Upper Mara River Basin, Kenya: Results of a modeling study to support better resouce management |
| Authors: | Mango, L.M., A.M. Melesse, M.E. McClain, D. Gann and S.G. Setegn |
| Year: | 2011 |
| Journal: | Hydrology and Earth System Sciences |
| Volume (Issue): | 15(7) |
| Pages: | 2245-2358 |
| Article ID: | |
| DOI: | 10.5194/hess-15-2245-2011 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| Broad Application Category: | hydrologic only |
| Primary Application Category: | climate change and land use change |
| Secondary Application Category: | hydrologic assessment |
| Watershed Description: | Nyangores subbasin of the 13,750 km^2 Upper Mara River basin in southern Kenya |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | Abstract. Some of the most valued natural and cultural landscapes
on Earth lie in river basins that are poorly gauged and
have incomplete historical climate and runoff records. The
Mara River Basin of East Africa is such a basin. It hosts the
internationally renowned Mara-Serengeti landscape as well
as a rich mixture of indigenous cultures. The Mara River
is the sole source of surface water to the landscape during
the dry season and periods of drought. During recent years,
the flow of the Mara River has become increasingly erratic,
especially in the upper reaches, and resource managers are
hampered by a lack of understanding of the relative influence
of different sources of flow alteration. Uncertainties about
the impacts of future climate change compound the challenges.
We applied the Soil Water Assessment Tool (SWAT)
to investigate the response of the headwater hydrology of
the Mara River to scenarios of continued land use change
and projected climate change. Under the data-scarce conditions
of the basin, model performance was improved using
satellite-based estimated rainfall data, which may also improve
the usefulness of runoff models in other parts of East
Africa. The results of the analysis indicate that any further
conversion of forests to agriculture and grassland in the basin
headwaters is likely to reduce dry season flows and increase
peak flows, leading to greater water scarcity at critical times
of the year and exacerbating erosion on hillslopes. Most
climate change projections for the region call for modest
and seasonally variable increases in precipitation (5–10 %)
accompanied by increases in temperature (2.5–3.5 deg. C). Simulated
runoff responses to climate change scenarios were
non-linear and suggest the basin is highly vulnerable under
low (−3 %) and high (+25 %) extremes of projected precipitation
changes, but under median projections (+7 %) there
is little impact on annual water yields or mean discharge.
Modest increases in precipitation are partitioned largely to
increased evapotranspiration. Overall, model results support
the existing efforts of Mara water resource managers to protect
headwater forests and indicate that additional emphasis
should be placed on improving land management practices
that enhance infiltration and aquifer recharge as part of a
wider program of climate change adaptation. |
| Language: | English |
| Keywords: | |