The impact of land cover and land use on the hydrologic response in the Olifants
Date
2008-10-23T08:20:25Z
Authors
Ncube, Mthokozisi
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Abstract
Water availability in Southern Africa is highly variable both in time and space, thereby
exposing the region to high risks in water availability. This is further compounded by
numerous human activities which have significant impact on water resources. The
brunt of the risks associated with water scarcity is particularly heaviest on resourceconstrained
farmers who depend largely on rain-fed agriculture for subsistence. With
continuously increasing demands on the water resources, the need for a better
understanding of the hydrological systems becomes crucial as it forms the gateway for
providing reliable information for managing water resources.
It is also increasingly becoming more important to address land and water linkages
because land use decisions are water use decisions. Operational hydrology provides an
insight into the effects of man-made changes, the foreseeable hydrological
characteristics at a given site, and the long-term prediction of the future hydrological
effects of human activities. This provides for a more holistic approach in managing
land and water resources as well as the impact of land use on partitioning rainfall into
streamflow.
This report discusses the application of the SWAT model to the B72E - F quaternary
catchments in the Olifants Water Management Area to assess streamflow generation
and the effects of human-environment interactions on the hydrology. Results show an
expected correlation between land cover and the hydrologic response where an
increase in land cover corresponds to a reduction in the streamflow. Range grass shows
a higher reduction in the streamflow followed by forestry with arid land giving the
highest increase in streamflow. Prediction in the similar neighbouring and ungauged
B72A catchment gives a MAR of 68mm.
Additionally, a rigorous analysis of the concepts of a local hydrological model, HDAM,
is done with respect to rainfall which is the main driver of the model. Modifications of
some of the relationships used in the model are suggested with the potential of
streamlining the model and making it more applicable in the region.
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Keywords
hydrology, land use and land cover, SWAT, Olifants Catchment