The hydrology of the Kudumela Wetland, Limpopo Province of South Africa was studied from November 2005 to April 2007, involving both fieldwork and laboratory analyses. This study presents the results of an investigation of the hydrology of the Kudumela Wetland in South Africa, and its contribution to dry season flow in the Mohlapitsi and Olifants Rivers. Initially, 40 Piezometers were installed along seven transects and water levels monitored in order to understand water table level characteristics (fluctuations) with time. Water levels in transects one, three, the right bank portion of transect four and transect six showed fluctuations. Transect two, the left bank portion of transect four and transect five did not show significant temporal changes. The relationships between piezometer water levels, rainfall in the study area and stream flow observed at a river gauging station are not clear. The river within the wetland is a gaining stream because the water table level elevation is above that of the river. This indicates that the wetland is feeding the river. The northern part of the wetland (T1 and T2) is affected by artificial drains and most of the piezometers closest to the river channel showed the lowest variations. The relationships between rainfall, groundwater, and surface water at this site shows that stream flow did not respond quickly to precipitation as expected, even in months when rainfall increased (for example, 74 and 103mm during 08/02/06 and 18/02/06 respectively), and the groundwater levels did not show fluctuations, indicating that groundwater responds gradually to precipitation, and that the relationship between rainfall, groundwater and surface water is complex. The environmental stable isotopes (deuterium and oxygen-18) and the radioactive isotope (tritium) were analyzed, along with field observations of electrical conductivity (EC), pH, total alkalinity (Talka) and some major and minor dissolved ion analyses for tracing water dynamics in the study area. A total of 39 water samples was taken and analyzed from boreholes, auger holes, right bank and left bank drains, various points along the river and springs in four sampling visits to the wetland. The results did not clearly provide a temporal record of isotope and chemical variations in the various sources. Results from the most extensive sampling survey in April 2007 provide the most comprehensive overview of hydrological relationships. Clustering of the stable isotope data suggests that the water samples of upstream and downstream river, auger holes further south and most drains clustered together suggesting a common water source and almost all samples fall above the global (GMWL) and local (Pretoria MWL) meteoric water lines, while some fall between the global and Pretoria meteoric water lines. Six representative water samples were analyzed for major ion concentration. Both cation (Ca, Mg, K, and Na) and anion (HCO3, SO4, Cl, and NO3) analyses in November 2007 confirmed conclusions reached from field observations. The analysis shows that a single type of water (Ca, Mg-HCO3) is involved in the study area. In almost all major ion plots, the right bank drains, upstream river and downstream river samples grouped together in a single cluster. As the means for reliable river flow measurements were not available, except for the gauging station at the outlet of the valley, rough, semi-quantitative estimates were made during several field visits. These, suggest considerable losses of river flow into the gravel/boulder beds at and below a gabion dam at the head of the valley. Three major and several other left bank springs and right bank drains at transects T1 and T2 contributed to the river flow at all times. Along with the isotopic and chemical evidence, these observations have lead to a hypothesis that river water enters the wetland and flows back to the Mohlapitsi River through boulder beds underlying the wetland and through drains on the surface of the argillaceous aquitard covering the more conductive boulder beds. Deeper dolomitic groundwater does not appear to contribute to the water balance at least in the northern half of the wetland. Although environmental isotope and hydrochemistry results may not unequivocally prove this hypothesis they do not contradict it.

PhDENV (Hydrology) / Department of Hydrology and Water Resources / This study developed operating rules for groundwater supply from a probabilistic (risk-based) approach. Groundwater supply systems are often operated without relating groundwater yield/availability to demand which makes groundwater resource planning and management challenging and unpredictable. Risk-based approaches for developing groundwater operating rules comprehensively incorporate assurance of supply and also account for uncertainty due to model inputs, model structure and climate variability. A groundwater resource unit (GRU) was delineated and its hydrogeological conceptual model developed. Automatic curve matching was used to identify appropriate aquifer models and test solutions for estimating hydraulic characteristics (storativity, transmissivity and hydraulic conductivity) based on Aquifer Test Solver (AQTESOLV) Pro version 4.5. Limited groundwater levels and rainfall data were infilled and/or extended using Output Error-Nonlinear Hammerstein Weiner (OE-NLHW) and non-parametric regression (NPR), respectively. Performances of these models were based on relative error (RE), correlation coefficient (COR), root mean square error (RMSE), coefficient of determination (R2) and Nash Sutcliffe coefficient of efficiency (NSE). A program for generation of monthly groundwater levels for the GRU was coded in FORTRAN based on the revised version of the Pitman model (referred to as GW-PITMAN model). The model was calibrated using groundwater levels from a neighbouring borehole due to lack of observed representative data for the GRU. Validation was done by establishing the realistic nature of simulated runoff, recharge and groundwater levels. A Variable Length Block (VLB) bootstrapping model was used for simultaneous generation of stochastic inputs (rainfall, evaporation and groundwater levels) of the groundwater operating rules model. Operating rules were developed from statistical analysis of 100 base yields for the GRU simulated from 5-year long stochastically generated sequences (with length of 34 years) of rainfall, evaporation and groundwater levels. The hydrogeological conceptual model indicated presence of faults and diabase dykes which influence preferential flow paths and storage of water in the aquifer. Identified aquifer test solutions were found to be suitable for estimation of hydraulic characteristics, since they had generally good model fits and low mean residual errors. Heterogeneous aquifer types were identified though leaky aquifer dominated. Storativity, transmissivity and hydraulic conductivity values ranged from 0.0003-0.060, 0.78-12.3 m2/day and 0.074-0.460 m/day, respectively, indicating limited storage with potential for local groundwater supply for private consumption. Graphical fits for observed and estimated rainfall and groundwater levels were mostly comparable, though scatter plots indicated cases of underestimation and overestimation of observed values. R2, COR, NSE, RMSE and RE values were 0.76 and 0.7, 0.87 and 0.84, 0.75 and 0.68, 3.67 and 3.03 mm and 30 and 29% for both calibration and validation runs, respectively, for NPR model. R2, COR, NSE, RMSE and RE were 0.99 and 0.86, 0.97 and 0.93, 0.99 and 0.84, 0.03 and 0.01 m and 0.08 and 0.11% for both calibration and validation runs, respectively, for OE-NLHW model. The models were therefore found to have efficient calibration and validation, and were thus, suitable for data extension. Estimated groundwater levels, streamflow and groundwater recharge for both calibration and validation runs of the GW-PITMAN model, generally fluctuated with changes in rainfall, indicating that they are realistic. Majority (9 out of 10) of the historical statistics were mostly well preserved by VLB, except for skewness. Historic highest groundwater levels were also not well preserved. Superimposing the cumulative demands on the base yield curves and analysis of percentages of water demands that can be supplied indicated that the groundwater system could not meet the water demands at all times. To promote sustainable multipurpose use of water that can enhance rural livelihoods, allocating water using priority classification was found to be essential. Operating rule curves for groundwater supply were derived using a risk-based approach. The operating rule curves indicated that if priority classification is used all water demands are met up to maximum groundwater level of 25 m. The developed operating rule curves are therefore expected to improve water supply to both domestic and productive water uses, if they are adequately implemented and hence improve livelihoods. The procedures followed in developing risk-based groundwater operating rules for Siloam Village were summarised to assist in their application in any delineated groundwater resource unit. Though minimal infrastructure is available to support implementation of the operating rules, additional monitoring boreholes are required to aid in estimation of average groundwater levels for further calibration and validation of the GW-PITMAN model. Detailed geological and geophysical investigation are required to improve on characterisation of the GRU and its hydrogeological conceptual model. Undertaking a study of this nature in other areas including those which are data-scarce could promote wide implementation of risk-based groundwater operating rules. / NRF

Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: South Africa's system of socio-economic development planning is complex and ine ective. There are many regulatory authorities involved, often with unclear responsibilities and inadequate procedures of implementing objectives. Planning for development in South Africa needs to take various factors into account. Economic growth is pursued, while social imbalances are addressed and the environment is protected against unreasonable damage. The term Sustainable Development is an important concept in the vision of many of the regulating authorities, however, the implementation of sustainability is di cult. This study considers an approach which aligns activities in a specifi ed region to the vision and objectives of the applicable regulatory authorities, as an alternative to achieving objectives strictly through enforcing regulations. This thesis developed an integrated evaluation model which can be used to evaluate the alignment of a small-scale farm to the visions and objectives of certain regulatory authorities. Four small-scale farms in the Letaba catchment of the Limpopo Province were used as a case study to be evaluated against national and regional development visions. On a national level the National Development Plan (NDP), the National Framework for Sustainable Development (NFSD), the Integrated Sustainable Rural Development Strategy (ISRDS) and the principles of Water Allocation Reform (WAR) were regarded. For regional categorisation, the relevant municipal Integrated Development Plan (IDP), Spatial Development Framework (SDF), Local Economic Development (LED) plan and the applicable Catchment Management Strategy (CMS) were considered. The Letaba catchment area has speci c development constraints regarding water. For this reason, the impact the four farms have on the water of the region was evaluated in addition to their alignment with regional development visions. The hydrological evaluations were performed through the use of the Soil and Water Assessment Tool. Hereby it was determined whether objectives of development planning were realistic in terms of water availability. It was established that the location of a farm is a determining factor of the impact it has on the catchment area's water supply. The developed Integrated Evaluation Model combined all the visions and objectives of the mentioned strategic documents to speci cally assess the contribution a small-scale farm makes. The evaluation results provide insight into the alignment of activities to the ideals of a region and can be useful when formulating actions to reach a common vision. Small-scale farms are well-aligned to the objectives of WAR, the CMS and ISRDS. The farms have a limited contribution to the ideals of the NDP and NFSD and results against the IDP, the SDF and the LED di er considerably for each farm. Furthermore, the results of the farms' alignment with regional objectives do not correspond to the hydrologically ideal locations. Therefore, the development of small-scale farming should take hydrological information into consideration. The Integrated Evaluation Model proves to be valuable, understandable and applicable to evaluate the alignment of small-scale farms to the visions of regulatory authorities. / AFRIKAANSE OPSOMMING: Suid-Afrika se sisteem van beplanning vir sosio-ekonomiese ontwikkeling is ingewikkeld en one ektief. Daar is verskillende regulatoriese owerhede betrokke wat maklik aanleiding gee tot onsekerheid ten opsigte van verantwoordelikhede asook tot onvoldoende benaderings tot implementering. Om ontwikkeling in Suid-Afrika suksesvol te laat geskied, moet verskeie faktore inaggeneem word. Behalwe vir die strewe na ekonomiese groei, moet sosiale agterstande gelyktydig aangespreek word en moet hierdie ontwikkeling van so 'n aard wees dat die omgewing nie onnodige skade lei nie. Volhoubaarheid is 'n gemeenskaplike ideaal van die meeste partye betrokke by die beplanning van Suid-Afrika se ontwikkeling. Die implementering van hierdie oogmerk is egter onduidelik. Hierdie studie oorweeg 'n benadering wat alle handelinge in 'n bepaalde gebied in ooreenstemming bring met die visie en doelwitte van die toepaslike regulatoriese owerhede. Hierdie benadering word as 'n alternatief gestel teenoor 'n benadering om doelwitte slegs deur regulasies te bereik. Hierdie tesis het 'n Geïntegreerde Evalueringsmodel ontwikkel wat die mate waartoe 'n klein plaas 'n bydrae maak tot die visie en doelwitte van regulatoriese owerhede meet. Vier kleinskaalse boerderye in die Letaba Opvangsgebied in Limpopo was ondersoek as 'n gevallestudie. Hierdie plase is geëvalueer teen nasionale- en streeksontwikkelingsvisies. Op 'n nasionale vlak is die Nasionale Ontwikkelings Plan (NOP), die Nasionale Raamwerk vir Volhoubare Ontwikkeling (NRVO), die Geïntegreerde Volhoubare Landelike Ontwikkelings Strategie (GVLOS) en die waardes van die Water Toekenning Hervorming (WTH) beskou. Ten opsigte van streeksontwikkeling, is die betrokke munisipale Geïntegreerde Ontwikkelings Plan (GOP), die Ruimtelike Ontwikkelings Raamwerk (ROR), Plaaslike Ekonomiese Ontwikkeling (PEO) plan en die gepaste Opvangsgebied Bestuurs Plan (OBP) inaggeneem. Water is 'n beperkende faktor tot ontwikkeling in die Letaba opvangsgebied. Omrede, word die vier plase se impak op die watertoestand van die gebied bepaal, sowel as die bydrae tot die visie van die regulatoriese owerhede. 'n Opstelling van die studie-area is gemaak met die Soil and Water Assessment Tool ten einde hidrologiese a eidings te maak. Hierdeur is bepaal of die visies en doelwitte soos gestel deur die beplanningsdokumente vir ontwikkeling, realisties is ten opsigte van die waterbeskikbaarheid. Die studie het bevestig dat die ligging van 'n plaas 'n bepalende faktor is tot die plaas se uitwerking op die gebied se water. Die ontwikkelde Geïntegreerde Evalueringsmodel kombineer die visies en doelwitte van die bogenoemde strategiese dokumente om die bydrae van 'n klein plaas te meet. Die evalueringsresultate verskaf insigte rondom die ooreenstemming van plase teenoor die visie van 'n streek en kan nuttig gepas kom wanneer spesi eke aksies beplan word om 'n gemeenskaplike doelwit te bereik. Kleinskaalse boerdery is in lyn met die doelwitte soos bepaal deur die OBP, GVLOS en WTH. Die bydrae wat die plase ten opsigte van die NOP en NRVO se ideale maak is egter beperk. Verder verskil die resultate grootliks vir elke plaas ten opsigte van die bydrae gelewer tot die visies van die GOP, ROR en PEO. Gewensde resultate ten opsigte van bydrae tot ontwikkelingsvisies het nie ooreengestem met die liggings wat aanbeveel is deur die hidrologiese studie nie. Dus moet hidrologiese inligting inaggeneem word tydens besluitneming vir die ontwikkeling van kleinskaalse boerdery. Die Geïntegreerde Evalueringsmodel bied waarde, is toeganklik en is toepaslik om kleinskaalse boerdery te meet tenoor die visies van regulatoriese owerhede.

MESHWR / Department of Hydrology and Water Resources / See the attached abstract below

MESHWR / Department of Hydrology and Water Resources / See the attached abstract below

MSc (Botany) / Department of Botany / The use of disturbance in the management of Savanna is a common rangeland practice in South Africa. A two-season trial was established in June 2016 and December 2016 to evaluate the effects of disturbance of different intensities on wetland belts in the Nylsvley Nature Reserve. The disturbances were in three different belts of different grass types at different intensities. The experimental treatments consisted of two different intensities, namely; high (H) and low (L). The Cyperus amabilis belt was regarded as site 1, the Sporobolus africanus as site 2, and the Themeda triandra as site 3. Seventeen kites were contracted in each belt, two times 1 m × 1 m at high and low intensity, followed by two times 2 m × 2 m one at high intensity. The results showed that disturbance affects the topsoil by removing the soil which is rich in nutrients producing pioneer species for the first few months and then original species were seen inhibiting again. / NRF