Changes in climate due to anthropogenic influences are expected to affect both hydrological
and agricultural systems in southern Africa. Studies on the potential impacts of climate
change on agrohydrological systems had been performed previously in the School of
Bioresources Engineering and Environmental Hydrology (School of BEEH). However,
refinement of these modelling tools and restructuring of the databases used was needed to
enable more realistic and dynamic simulations of the impacts of changes in climate.
Furthermore, it was realised that modifications and linkages of various routines would result
in a faster processing time to perform climate impact assessments at the catchment scale.
Baseline ("present") climatic information for this study was obtained from the School of
BEEH's database. Scenarios of future climate were obtained from six General Circulation
Models (GCMs). Output from the five GCMs which provided monthly climate output was
used in the climate impact assessments carried out. Potential changes in variability of rainfall
resulting from climate change was assessed using the daily climate output from the sixth
GCM. As the spatial resolution of the climatic output from these GCMs was too coarse for
use in climate impact studies the GCM output was interpolated to a finer spatial resolution.
To assess the potential impact of climate change on water resources in southern Africa the
ACRU hydrological modelling system was selected. The ACRU model was, however, initially
modified and updated to enable more dynamic simulation of climate change. In previous
hydrological studies of climate change in southern Africa Quaternary Catchments were
modelled as individual, isolated catchments. To determine the potential impact of changes in climate on accumulated flows in large catchments the configuration of the Quaternary
Catchments needed to be determined and this configuration used in ACRU.
The changes in hydrological responses were calculated both as absolute differences between
future and present values and the ratio offuture hydrological response to the present response.
The large degree of uncertainty between the GCMs was reflected in the wide range of results
obtained for the water resources component of this study. In addition to the climate impact
studies, sensitivity and threshold studies were performed using ACRU to assess the
vulnerability of regions to changes in climate.
Potential change in the yields and distributions of parameters important to agriculture, such
as heat units, crops, pastures and commercial tree species were assessed using simple crop
models at a quarter ofdegree latitude / longitude scale. Most species were simulated to show
decreases in yields and climatically suitable areas. There are many sources of uncertainties
when performing climate impact assessments and the origins of these uncertainties were
investigated. Lastly, potential adaptation strategies for southern Africa considering the results
obtained are presented. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2001.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/4554 |
| Date | January 2001 |
| Creators | Perks, Lucille Annalise. |
| Contributors | Schulze, Roland E. |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
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