INTRODUCTION AND SCOPE OF INVESTIGATION Irrigated land in South Africa currently amounts to approximately 1.3 million hectares. Agricultural water use is estimated to comprise the largest amount of water users in Southern Africa, with much of the region dependent on sufficient water of adequate quality for survival. The Vaalharts is the largest irrigation scheme in South Africa. Approximately 32 000 hectares of land is currently being irrigated. The salinity of the irrigated water has steadily increased over time (Herold and Bailey, 1996). Several research projects have been undertaken to determine the fate of added salts. The conclusion in these reports is that a very large proportion of the salts added to the subsurface due to irrigation are not returned to the surface water. A sink for these salts is therefore believed present. Research into the salt balance of the area and the effect of the salts on soils and crops have suggested that the majority of this salt is being leached through the soil and into the groundwater resources underlying the irrigated area. The underlying aquifer was believed to have a limited storage capacity. Once this capacity is exceeded, a flow reversal is expected. This process is likely to add a tremendous salt load (roughly estimated to be in the order of 100000t/annum (Herold and Bailey, 1996)) to an already stressed river system. The adverse effects of such an addition would be catastrophic to the irrigation scheme and the receiving aquatic environment. This thesis aims to determine the processes leading to the scenario outlined above.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-08252004-115513 |
| Date | 27 August 2004 |
| Creators | Ellington, R. G |
| Contributors | DR B H USHER |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://lourie.uovs.ac.za//theses/available/etd-08252004-115513/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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