Multi-Method Evaluation of Pumping Test Data to Characterize the Fractured Meta-Carbonate Aquifer at the Ntanisha Well-Field in Chongwe District, Zambia

Abstract

Groundwater remains a vital resource for socio-economic development; however, increasing demand has intensified pressure on aquifers, heightening their vulnerability to depletion and contamination. In Zambia, limited hydrogeological data further increases the risk of over-abstraction and inefficient well-field operation. This study presents a multi-method evaluation of pumping test data to characterize the fractured metacarbonate aquifer at the Ntanisha well-field in Chongwe District using constant-rate, step-drawdown and recovery pumping tests conducted on four production boreholes supplying Chongwe Town. Time-drawdown data were analysed using conventional analytical methods and the Flow Characteristic (FC) method to estimate transmissivity, hydraulic conductivity, storage coefficient and specific capacity. Results indicate a heterogeneous fractured aquifer with transmissivity ranging from 5.63 to 43.95 m²/day, storage coefficients from 8.7*^10-6 to 4.96*^10-2, and hydraulic conductivity from 0.0561 to 0.3957 m/day indicating confined to semi-confined behaviour. Boreholes intersecting well-developed fracture zones exhibited higher specific capacities (0.58–0.64 Ls⁻¹m⁻¹) and sustainable yields (80 m³/day to 292.9 m³/day). The analytical approaches show that reliance on constant-rate pumping test alone can overestimate safe abstraction, whereas integrating the FC method provides a more conservative and operationally robust basis for well-field management. The study highlights the value of multi-analytical pumping test interpretation for groundwater development and sustainable management of fractured metacarbonate aquifers across similar hydrogeological settings.