Management of a Karoo fractured-rock aquifer system – Kalkveld Water User Association (WUA)

Abstract

Due to large-scale development of groundwater resources for irrigation purposes the Kalkveld area has been identified by DWAF as an area where a water user association (WUA) should be established in order to achieve better management of the resource. The area represents typical Karoo type fractured-rock aquifers, which consist mainly of sandstone, mudstone, shale and siltstone. The majority of boreholes drilled in Karoo formations have very low immediate yields (<1 ℓ/s). However, large volumes of groundwater are pumped from boreholes in the Kalkveld area for irrigation of commercial crops. Thus, these aquifers have a more complex and unpredictable behaviour than normally described in the literature. Groundwater management units have been delineated based on: similar hydraulic properties; recharge characteristics; land use; geology (including the distribution of surface calcrete deposits); rainfall; and hydrochemistry.

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