Health, food and water security-South Africa

The potential impact of a changing climate on the availability of water resources has been ranked as the 3rd highest risk facing Umgeni Water, the water utility responsible for supplying potable water to consumers within the Mgeni Catchment including those in the Greater Durban‐Pietermaritzburg area, South Africa. This case study will focus on improving the understanding of the potential changes in water quality in the uMngeni catchment under a future climate. To achieve this climate impact indicators (CIIs) that are relevant to water quality issues in the catchment will be produced for the future.


Issue to be addressed

The greater uMngeni catchment, South Africa is under severe stress to supply the drinking-water demand for two large residential areas (Durban and Pietermaritzburg), and several smaller ones. The four large reservoirs in the catchment are becoming eutrophic, mainly due to nutrient additions to the river systems from agricultural activities, aging sanitation infrastructure and scattered informal settlements that lack basic sanitation infrastructure. These fast growing informal settlements together with inadequate infrastructure in some cities contaminate the streams with raw sewage. Public health and safety are affected when bacteria counts exceeded 400 per 100 ml (SA Guidelines); the actual concentrations in the uMngeni river systems have reached up to 1 000 000 counts per 100 ml. A changing climate into the future could exacerbate this problem.

Decision support to client

The climate impact indicators (CII’s) produced through this project will assist the bulk water service providers and municipalities in the catchment to better understand how the nutrient and pathogen loadings will change temporally and spatially through the uMngeni catchment under future climate scenarios. The CII’s will allow for an understanding of the potential changes in nutrient loading and nutrient concentrations under a future climate, as well as assisting with identifying hotspot areas of concern where intervention will be required by the bulk water service providers and municipalities.

Temporal and spatial scale

The hydrological modelling will be undertaken for the greater uMngeni catchment (4 349.4 km2) with results summarized to the thirteen water management units that have been delineated in the catchment.

The period 1960 – 1999 will be used to produce the historical (benchmark) CII’s as high quality data is available for this period. Future climate scenarios to 2050 will be considered.


Poster displayed at the Kick–Off meeting, 7/8 September 2017, Norrköping, Sweden