E. Pretorius

Catchment Hydrology Management Using GIS:Case Study Of The Modder River Basin,South Africa

Water is constantly flowing through the landscape in response to weather events and most often, in the form of streams and rivers. This water flow carries micro-organisms, dissolved chemicals and sediment, which define water quality. We need to understand these flowand quality-patterns and how they change in order to properly manage the water resources of river basins. Hydrological analysis and modelling of water flow and quality are provided by hydrological simulation models, whilst GIS describes the physical environment through which the water flows. Integrating hydrological modelling and GIS involves connecting geospatial data, which describe the physical environment, with hydrological process models, which explains how water moves through the environment. Even though there is a significant synergy between geospatial and temporal water resources information, it is difficult to capture because, up to now, the data (geospatial and temporal) have been held in different formats and archiving environments. One of the aims of this project was therefore to create a geodatabase (GBase) where geospatial and temporal data are captured and stored in one environment. Another aim was to achieve communication and data exchange between GBase, HYDSTRA, a hydrological database and BASINS, an environmental analysis system. The overall purpose, however, was to create an integrated platform, including the above programmes, to provide tools to pre-process data for different independent models, which can then be used to investigate the impact of changes or developments in the river basin. The Modder River Basin, which forms part of the Upper Orange Water Management Area in South Africa, was used as study area.

THE IMPACT OF INFORMAL LIVING CONDITIONS ON WATER QUALITY IN THE BLOEMFONTEIN MUNICIPALITY

ABSTRACT Nonpoint source pollution from developing communities can adversely affect the natural functioning of river ecosystems and thus have severe economic and health implications for downstream users. The causes and sources of nonpoint source pollution are situated within the socio-economic and institutional environment of the community. The socio-economic conditions under which the people in a developing community live and the implications that this has on the quality of the water resources were identified by means of a field survey in the study area. Although community members tend to be positively orientated towards the prevention of water pollution, the results indicate that misperceptions and ignorance exist with regard to factors that cause water pollution and degrade water resources. From the results of the survey it is apparent that the variety of factors underlying pollution from developing communities are highly inter-dependant and a holistic approach to identify and address these problems, as well as their impact on the water resource, is necessary.

Implications Of Rainwater Harvesting In ARiver Basin Management: Evidence FromThe Modder River Basin, South Africa

In a new paradigm shift related to integrated water resources management in the context of a river basin, attention is being drawn to consider the upstream and downstream impacts on the various water use entities. The river basin is increasingly acknowledged as the appropriate unit for analysis and management of water resources, especially as water availability becomes the primary constraint to agriculture. The irrigated agriculture in the Modder river basin, in the central South Africa, draws water from river pools and weirs. However, many small-scale farmers rely on rain-fed farming. A few years ago, the ISCW-ARC introduced a rainwater harvesting technique for these farmers, which is reported to have increased crop yield significantly compared to conventional practices. The research questions were: what is the potential expansion of this technique? and; what will be the implications of this practice on the downstream users if applied on a wider scale? A field survey showed that a fairly rapid spread of the application of the technique can be expected within the scope of home yard size, but no significant spread to community gardens and beyond is expected in the short term because of socio-economic constraints such as poverty, and lack of appropriate tools and basic farming skills.