Voorsiening en benutting van landbouwater in die Ohrigstad-vallei

M.Sc.Because of South Africa's high rate of population growth, it becomes more difficult to supply in the basic needs of people, of which water for personal use and food may be the most important. South Africa is a dry country with weak and marginal soils in most parts. This necessitates the effective use of these important natural resources. Recent legislation forces commercial agriculture to use care and sustainable methods in their resource use. Justification must also be made for ratio of resources used compared to the product delivered from that use. Therefore it is necessary to examine this use and the role it plays in the supply of basic human needs as well as economic growth. A study of these agricultural resources cannot be undertaken on a large scale, because every agricultural is unique. The purpose of this study is to generate an idea of the physical and agricultural environment of the Ohrigstad valley. This research is mostly based on the assimilation of previous studies and the comparing of results over time. This information is used to compare results from previous studies and to determine possible trends in factors_such as rainfall. A further study of the natural resources that attribute to effective commercial agriculture are made. From here the emphasis falls on the use and distribution of irrigation water to these activities in the valley. These natural sources of water and their means of distribution are studied and described. Rainfall as a direct source of water is determined by information regarding rainfall and microclimatic circumstances. Surface and subterraneous sources are described by information on the general hydrology and geohydrology of the study area. In such an environment there are many factors affecting the supply of water to agriculture such as: forestry, afforestation of riparian zones, as well as geological occurrences in the streambeds. Possible solutions for problems posed by these factors are discussed in relation to previous studies in similar areas, as well as the economic benefits that may be reaped because of such change. Finally the role that legislation (Water Act 36 of 1998) plays in the use of water by agriculture is discussed in terms of possible impacts that it may have on commercial agriculture in the area. In this study it has become clear that a lot more research must be done in such a project before any trends can be related and proved