HYDROGEOLOGICAL DESCRIPTION OF NYIMBA DISTRICT AQUIFERS
This map for Nyimba district was extracted from the hydrogeological map of Zambia. This was developed as a tool to facilitate the efficient use and management of water resources, including groundwater, as stipulated by the Zambian water resources management act of 2011. It shows spatial distribution of aquifers, aquitards and aquicludes and describes the lithological characteristics and quantitative hydraulic potential of major rocks with Zambia.
Nyimba district aquifers of alluvial deposits are relatively high potential for development in Luangwa basin. All rocks have been weathered to some extent through the process of tectonic deformations and these zones form aquifers. Weathered or fractured gneiss, granite, schist and quartzite are main aquifers for groundwater supply in plateau area. However, groundwater from sandstone underlying the alluvial aquifers are said to be brackish and is not suitable for drinking. South east, southern, south west and parts of northern part of Nyimba are characterized of undifferentiated kundelungu, lower roan quartzite, muva sediment, granite) which have low groundwater potential. The high yielding aquifers stretch from the central part of the district to the north eastern part. The narration below shows the different aquifers and the groundwater potential.
A – Moderately productive, intergranular, predominately unconsolidated aquifer (0,1 – 15 l/s) (mainly Alluvial Sands and Gravels & Kalahari group)
B – Highly productive aquifer (0,1 – 70 l/s) (mainly upper Roan Dolomite & Kundelungu Limestone)
C – Moderately productive, fissured aquifer (0,1 – 15 l/s) (mainly Karoo Sandstone)
D – Locally productive, fissured aquifer (0,1-10 l/s) (mainly undifferentiated kundelungu, lower roan quartzite, muva sediment, granite)
E – Stratum with intermediate characteristics (0 – 2 l/s) (mainly low yielding formations of Karoo Basalt, mine series Shales & basement Gneiss)
F – Unproductive formations (mainly Karoo Shales, Metamorphic & Igneous rocks