Land-use on water quality of the Bottelary River in Cape Town, Western Cape

Abstract

Freshwater scarcity and river pollution has become a serious challenge for governments and scientists. Worldwide, governments have a responsibility to provide their populations with enough clean water for their domestic needs. Scientists will have an enormous task to find a way to purify polluted water, because of its vital role in human lives and an increasing demand for water consumption due to population growth. Although the water from the Bottelary River is used on a daily basis for farming activities, its pollution level as well as spatial distribution of effluents in the catchment is unknown. In the present study, I took monthly water samples from six sampling points for laboratory analysis. The laboratory determined concentration levels of phosphorous, chloride, nitrate, and nitrate nitrogen (N03N), as well as the chemical oxygen demand (COD) and suspended solids from the samples. On the same occasion's pH, dissolved oxygen, electrical conductivity and temperature were measured in-situ using a multi-parameter reader. The results were then compared with the South African Water Quality Guidelines for Aquatic Ecosystems and for irrigation (DWAF, 1996a, 1996c). The non-point pollution source (NPS) model was used to generate predictions of the pollution level from the land-uses and use the data obtained from the field to validate the model predictions. Finally, I performed a two-factorial A One-way Analysis of Variance (ANOVA) without replication to assess the spatial and temporal variation of the measured variables along the river.

The findings of the study have shown that the concentration levels of some compounds are below the Target Water Quality Range (TWQR) set by the Department of Water Affairs and Forestry (DWAF, 1996a, 1996b, 1996c) while, the concentrations of chloride, total nitrogen and water quality variables such as electrical conductivity, suspended solids, are higher than the TWQR (DWAF, 1996a, 1996b, 1996c). Based on the above findings water of the Bottelary River can have negative effects on the environment and human lives because of the concentration level of these compounds. It was therefore recommended that, environmentally friendly measures and practices must be undertaken in order to decrease the pollution and avoid further pollution of the river.