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Using groundwater quality index and concentration duration curves for classification and protection of groundwater resources to improve access to clean water and sanitation, South Africa

IWRA 2021 Online Conference One Water, One Health
Theme 1: How can we better manage water for food and public health in a changing world?
Author(s): S.M. Nzama, T.O.B. Kanyerere and H.W.T. Mapoma

S.M. Nzama1; T.O.B. Kanyerere2 and H.W.T. Mapoma3

1. Reserve Determination, Department of Water and Sanitation, Pretoria, South Africa
2. Department of Earth Sciences, University of the Western Cape, Bellville, South Africa
3. Department of Physics and Biochemical Sciences, The Polytechnic, University of Malawi, Malawi

Keyword(s): Concentration duration curve, groundwater quality index, groundwater resource protection, hybrid methodology, sustainable development goals, water quality class


(a) Purpose or objectives and status of study or research hypothesis
The spatial and temporal aspects of groundwater quality in the Nseleni catchment, South Africa (SA) was investigated, its suitability for domestic use was considered, and required protection measures to sustain water supply were established.

(b) Key issue(s) or problem(s) addressed
The availability of sufficient, potable water is critical in fostering water supply, health, and for food security. However, water resources challenges related to water resources quality deterioration, and availability are evident, globally and locally. Therefore, water quality assessment for water resource protection and management is critical towards sustainable provision of potable water supply and in meeting sustainable development goals (SDGs) linked to clean water and sanitation.

(c) Methodology or approach used
Using a hybrid approach methodology based on multiple water quality resource assessment techniques such as groundwater quality index (GQI) and concentration duration curves (CDCs), seventy-two groundwater samples collected from 1994 to 2017 were analysed for physico-chemical (Na+, Ca2+, Mg2+, Cl-, SO4 2-, NO3-, F-, EC, pH) parameters.

(d) Results and conclusions derived from the project
Approximately, 33.3% of groundwater samples in the Nseleni catchment were found suitable for drinking when compared to the South African water quality guidelines. The use of a hybrid approach method showed that overall groundwater quality in the study catchment was classified as excellent for domestic water use when groundwater quality index was calculated to be 39.11. Groundwater quality reserve limits for groundwater resources protection were successfully established for the nine water quality parameters using concentration duration curves (CDCs). The study concluded that using groundwater quality index and concentration duration curves, it was feasible to classify groundwater resources for improved groundwater quality, to ensure sustainable water supply for food and public health in the South African context.

(e) Implications of the project relevant to selected conference theme, theory and/or practice
The study recommends the application of the hybrid method in various catchments of similar characteristics to the studied catchment for setting groundwater quality limits that would contribute towards achieving the goal of groundwater resources protection to minimize negative impact related to water quality and interrupted water supply in other catchments.

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