OVERVIEW OF THE IMPACT OF MINING ON THE ... - IIED pubs

3.15 The Chirundu sub-catchment
3.15.1 General description
3.15.1.1 Hydrology
This area comprises a series of small sub-catchments, whose rivers flow south-eastwards towards the Zambezi
Valley, incising relatively deep channels through the edge of the escarpment from the surrounding plateau.
None of these rivers are perennial and only contain appreciable flow after rainstorms.
The plateau inland of the Zambezi Escarpment comprises relatively undulating terrain with several small
wetland areas and seeps, as well as small sinkholes in areas underlain by limestone deposits.
3.15.1.2 Geology
The plateau is composed of quartzites and associated rocks, underlain by Karoo Supergroup sedimentary rocks
and basalt. These rock formations are deeply incised by the numerous streams flowing from the plateau to the
Zambezi River. High quality limestone deposits are found at a few places on the plateau, testifying to the
marine origin of these rocks. The Zambezi Mobile Belt contains several occurrences of gold.
3.15.1.3 Pedology, agriculture and land use
Soils in the sub-catchment can be divided into four groups:
• Very shallow, gravely soils derived from Upper Karoo sediments and basalts;
• Moderately deep sandy soils derived from Lower Karoo sediments;
• Moderately deep kaolinitic sandy to loamy sand soils derived from quartzites and associated rocks;
• Moderately deep, sandy loams on areas underlain by limestone deposits.
The sub-catchment experiences moderate rainfalls of around 800-850 mm on the higher-lying plateau, grading
down to some 650 mm per year in the Zambezi Valley.
Land use comprises a mixture of sparsely populated communal lands with subsistence agriculture, densely
populated urban areas of Lusaka and Chilanga, with commercial stock farming (beef cattle and goats) on the
plateau and some cash cropping and commercial farming of maize. Several small communities are located
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