Thesis (M.Sc.)--University of the Witwatersrand, Faculty of Science, 2011 / A multifactor ecological integrity index, focusing on freshwater ecosystems on a quaternary catchment scale, can be of great benefit to conservation planning. No ecological integrity index has previously been developed for South African quaternary catchments. In this study an index was developed based on three environmental surrogates: land cover, river integrity and fish species conservation status, with the intention of identifying quaternary catchments of highest conservation concern. By developing such an index, the aim was to provide a general indication of the degree to which catchments have been transformed from a natural environment to a human altered environment, thereby identifying catchments most in need of conservation. For the three available datasets, indices were developed using a five category point-scoring system. A score of one indicates a completely degraded environment and a score of five indicates a pristine environment. The original land cover data consisted of 49 different land cover types which were reduced to five land cover transformation scores. Available river integrity data already existed in five categories and a numerical score of one to five was applied to each category. Fish species conservation status was scored according to the IUCN red data list classifications on a similar basis. Subsequently, a weighted mean score expressed as a percentage was calculated for the three indices for each quaternary catchment. These indices indicate the degree of change/transformation from a natural system (100%) to a largely degraded system (20%). Ultimately, an ecological integrity index was calculated as a mean value of the three related but independent indices. However, the results of the developed ecological integrity index were not representative of real world conditions. This is largely attributed to the lack of complete data found in two out of the three datasets used in the study. Some of the main limitations encountered were the lack of river segment definitions within each catchment and the incomplete and un-systematic collected fish species data records. The land cover data, on the contrary, was of high definition and high standard. It is recommended that in the interim, the developed land transformation index, based on a detailed analysis of land cover, be used as an indicator index of ecological integrity of catchments

MSc., Faculty of Science, University of Witwatersrand, 2011 / A multifactor ecological integrity index, focusing on freshwater ecosystems on a quaternary catchment scale, can be of great benefit to conservation planning. No ecological integrity index has previously been developed for South African quaternary catchments. In this study an index was developed based on three environmental surrogates: land cover, river integrity and fish species conservation status, with the intention of identifying quaternary catchments of highest conservation concern. By developing such an index, the aim was to provide a general indication of the degree to which catchments have been transformed from a natural environment to a human altered environment, thereby identifying catchments most in need of conservation. For the three available datasets, indices were developed using a five category point-scoring system. A score of one indicates a completely degraded environment and a score of five indicates a pristine environment. The original land cover data consisted of 49 different land cover types which were reduced to five land cover transformation scores. Available river integrity data already existed in five categories and a numerical score of one to five was applied to each category. Fish species conservation status was scored according to the IUCN red data list classifications on a similar basis. Subsequently, a weighted mean score expressed as a percentage was calculated for the three indices for each quaternary catchment. These indices indicate the degree of change/transformation from a natural system (100%) to a largely degraded system (20%). Ultimately, an ecological integrity index was calculated as a mean value of the three related but independent indices. However, the results of the developed ecological integrity index were not representative of real world conditions. This is largely attributed to the lack of complete data found in two out of the three datasets used in the study. Some of the main limitations encountered were the lack of river segment definitions within each catchment and the incomplete and un-systematic collected fish species data records. The land cover data, on the contrary, was of high definition and high standard. It is recommended that in the interim, the developed land transformation index, based on a detailed analysis of land cover, be used as an indicator index of ecological integrity of catchments

The aquifer vulnerability of the Molototsi (B81G) and Middle Letaba (B82D) quaternary catchments was assessed to determine the influence of the vadose zone on the groundwater regime. Anecdotal evidence indicated that the aquifers may be vulnerable to pollution. The aquifer vulnerability was assessed by developing a new method RDSS. The RDSS method was developed by combining relevant vulnerability parameters of DRASTIC, GOD, EPIK, SEEPAGE, COP and SINTACS. RDSS evaluates the vadose zone as a pathway for pollutants by using the following four parameters namely: Recharge, Depth to water table, Soil type and Slope. Recharge was estimated using the Chloride-mass balance method. Depth to water table was measured in the field using a dipmeter. For inaccessible boreholes, data was requested from Groundwater Project Consulting Company. The seepage behaviour (soil type) was determined using parameters such as hydraulic conductivity, infiltration and percolation. Percolation and hydraulic conductivity was determined by undertaking percolation tests in accordance with SABS 0252-2:1993. Infiltration was determined using the double ring infiltrometer. Slopes were determined from the digital elevation method using ArcGIS software. High recharge was revealed in the lower parts of both B81G and B82D. Shallow depth to water level was revealed on the upper part of B82D and extended towards the lower part of B81G. Soil type relates to saturated vertical hydraulic conductivity, which was rated to be high in the northeast of B81G. Gentle (high influence due to preferential infiltration to runoff) slopes extend from the south towards the northern parts of both B81G and B82D. The four parameters (recharge, depth to water table, soil type, and slope) were overlaid using Weighted Sum, Weighted Overlay and Raster Calculator to produce the final vulnerability map. When using Weighted Overlay and Weighted Sum, rasters were given different percentages of influence in different scenarios. The Weighted Overlay tool inputs multiple rasters and sets all weights equal to 100%. The Weighted Sum tool inputs multiple rasters and sets all weight equal to 1.0. When using the Raster Calculator, rasters were evaluated by being added together without multiplying by the percentage of influence. The results obtained are discussed in detail with reference to the degree of vulnerability of these two densely populated rural areas. / Dissertation (MSc)--University of Pretoria, 2013. / Geology / unrestricted