Characterisation of surface water quality in the Luapula river basin and developing a WQImin model for potential inter-basin water transfer to the Kafue river basin.
Date
2025
Authors
Kazekula, Jovita
Journal Title
Journal ISSN
Volume Title
Publisher
The University of Zambia
Abstract
This study underscored the importance of water quality, providing insights for sustainable resource management in decision-making and development planning. The study focused on the Luapula River Basin (LRB) in Zambia, a potential donor for inter-basin water transfers to the Kafue River Basin (KRB). The research objectives included establishing baseline data on surface water quality and developing a cost-effective Water Quality Index model (WQImin) for regular monitoring. Data was collected during both the dry and wet seasons of 2022 and 2023, respectively. Two triplicate samples were collected from each sampling point using the grab sampling method from 57 sampling points in the dry season and 91 sampling points in the dry and wet seasons. The samples were analysed according to the standard methods for the examination of water and wastewater. In the dry season, Electrical conductivity (EC) ranged from 8 µs/cm to 225 µs/cm, Total dissolved solids (TDS) values ranged from 5 mg/L to 162 mg/L, pH values ranged from 6.19 to 8.4 and temperature ranged from 18.50C to 28.10C, potassium ranged from 1.7 mg/L to 12 mg/L, sodium ranged from 5.3 mg/L to 36.3 mg/L, chloride ranged from 8 mg/L to 55 mg/L, turbidity ranged from 1.39 NTU to 37.2 NTU, iron ranged from <0.002 mg/L to 2.234 mg/L, calcium hardness ranged from 6 mgCaCO3/l to 30 mgCaCO3/l and total hardness ranged from 20 mgCaCO3/l to 106 mgCaCO3/l. In the wet season, EC ranged from 6 µs/cm to 78 µs/cm, TDS ranged from 2 mg/L to 50 mg/L, pH ranged from 5.97 to 8.23 and temperature ranged from 20.80C to 28.80C, potassium ranged from < 0.01 mg/L to 2.4 mg/L, chloride ranged from 2 mg/L to 14 mg/L, turbidity ranged from 0.3 NTU to 24.9 NTU and iron ranged from <0.002 mg/L to 1.4 mg/L. Calcium and total hardness values were all below the detection limit of 1 mgCaCO3/l in the wet season. Total and faecal coliforms ranged from 0 CFU/100 ml to > 200 CFU/100 ml in both seasons. The concentrations of nitrate, phosphate and sulphate were below the detection limit of 0.01 mg/L. Similarly, the levels of manganese and lead were below the detection limits of <0.002 mg/L and <0.01 mg/L, respectively, in both seasons. The spatial-temporal variations were influenced by precipitation patterns, geological factors and anthropogenic activities, notably evidenced by elevated coliforms, iron, turbidity, sodium and chloride levels in specific areas. Hydro-chemical analysis characterised the surface water as a calcium–magnesium–bicarbonate type, indicating underlying geological geology rich in silicates. The WQI indicated that nine per cent of the sampling points in the LRB were unsafe, seven per cent were very poor, four per cent were poor, 2 per cent were good and 58 per cent were excellent for ambient purposes. The poor and unsafe WQIs in specific locations were mainly attributed to iron and turbidity. However, the overall WQI for the LRB was 38 per cent, indicating that the LRB has good-quality water making the implementation of inter-basin water transfer to the KRB feasible. A multi-linear regression model was developed for predicting the WQI value based on only five parameters (the WQImin value). The use of WQImin has the potential to save on the costs and time associated with water-quality monitoring. This model has the potential to aid in understanding challenges linked to inter-basin transfer and support the formulation of management strategies prioritizing water availability and ecosystem and livelihood sustainability.
Description
Thesis of Master of Science in Integrated Water Resources Management