Towards a GIS Platform for monitoring the water quality of the Jukskei river catchment: defining a sampling network

Abstract

To obtain an understanding of issues relating to water quality monitoring in the Jukskei River Catchment a users’ needs assessment is performed, through the use of literature review, interviews, and site visits. These are evaluated and used to develop a conceptual model giving a representation of a system that can address water quality concerns. The designed conceptual model for this research incorporates hydrological features, drainage systems, DEM extraction and thematic layers needed for the monitoring of water quality. The development of appropriate sampling locations is an essential step in the valuation, restoration, and protection of river water quality. Previous studies have focused on mathematical aspects and physical attributes of monitoring the quality of river water, however, human activities surrounding the river are often not considered in detail. In this study, an advanced water quality monitoring procedure is implemented using a combination of River Mixing Length (RML), information about human activities, and Geographic Information Systems (GIS) to identify representative sampling locations, with the purpose of optimizing the current locations of sampling points. The implementation of a new Potential Pollution Score (PPS) model of land use is used to prioritize the importance of each sampling point prior to selecting the most appropriate site for the entire catchment. Residential areas, mining and agriculture are amongst the 6 non-point sources integrated to develop representative sampling locations. Out of an optimal number of 11 242 sampling points, this research has identified 40 sites to propose. This number of sites is chosen because it is closer to the number of sampling points currently used (32) by the EISD for water quality monitoring of the Jukskei river catchment and thus does not stretch their funds.