The deep row trenching of ventilated improved pit-latrine (VIP) and waste water treatment works (WWTW) sludge is a unique alternative cost effective land application method that will prevent odour and health problems and may permit higher application rates than surface application. The goal of this research is to assess the environmental consequences of employing deep row incorporation of VIP and WWTW sludge to forest plantation lands for the production of Eucalyptus dunnii. The objectives are to monitor, define and quantify the fluxes of nutrients (nitrate and phosphorus) from the buried sludge to the surrounding soils, groundwater and surface water. The WWTW study was conducted on a forestry plantation located near the Shafton Karkloof Falls, about 10 km from Howick in the KwaZulu-Natal province of South Africa. The land for the research is owned by SAPPI, a timber plantation company. The trenching was done with stockpiled secondary sludge from Umgeni WWTW in Howick. VIP sludge trenching was done at the Umlazi E-ponds site in Durban owned by EThekwini Municipality. This site was formally used as a wastewater treatment plant sludge drying bed. The treatment works comprised three oxidation ponds and was operated until 1999, when it was decommissioned after a heavy flood, resulting in damage to the oxidation ponds. The sites were instrumented with wetting front detectors, piezometers and boreholes for collection and analysis of leachate from which were determined subsurface loss of nitrogen and phosphorus. Soil water status and groundwater levels were also monitored. Simulation of the process of water, nitrate and phosphorus transport was performed in order to aid the development of the sustainable management methodologies for land application and the trenching of VIP/WWTW sludge. The study focuses on the entrenched sludge to determine the concentration of pollutants, monitorchanges in concentration over time and to monitor the movement of solutes and any change taking place in the surrounding soil water and groundwater. The results contribute to the development of guidelines and protocols for VIP/WWTW sludge handling and trenching in South Africa. It was demonstrated that the nutrient migration processes can be approximated with the conceptual simplifications of the inputs to the model based on field evidence, soil survey data and applicable literature. In the study, it was found that high concentrations of nutrients were evident in the water infiltrating into and through the sludge in all trench types. The nitrate concentration median values in the trenches were 234mg/l and 36mg/l for SAPPI and Umlazi respectively, while the recorded median value for phosphorus was 1.0mg/l and 3.5mg/l for SAPPI and Umlazi respectively. However the effect of vertical seepage of nutrients, into the deep aquifer in fractured rock has not been observed in the deep borehole with the nitrate concentration median values at 5mg/l and 0.6mg/l for SAPPI and Umlazi respectively, while the phosphorus concentration median values were 0.03mg/l and 0.15mg/l for SAPPI and Umlazi sites respectively. The study revealed significant differences between the sandy alluvial site at Umlazi and the shale dolorite site at the SAPPI forests. Where an unsaturated zone below the entrenched sludge existed at the Umlazi site, nutrient transport was retarded, whereas in the shales of the SAPPI site, preferential delivery flowpaths transported high concentrations of nutrients rapidly from the entrenched sludge to the base of the hillslope. These mechanisms needed to be treated differently in the simulation exercise. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

Advances in hillslope hydrology have been numerous in the past two decades. However many of these advances have been highly site specific in nature, without identifying any means of linking processes across different spatial scales. Meaningful Prediction in Ungauged Basins (PUB) requires the understanding and observation of processes across a range of scales in order to draw out typical hydrological controls. Contempory tracer based methods of quantifying a combination of hillslope processes have identified hillslope geology as the main determinant in different catchment response types. A range of hillslope scale models have been developed in the last 20 years, using different levels of detail to simulate hillslope hydrological responses. Often the data heavy requirements of hillslope scale models make them impractical to apply at larger scales. While catchment scale models lack the ability to represent hillslope scale processes. In order to overcome this, a scale applicable model with the ability to represent hillslope and catchment dynamics is required to accurately quantify hillslope and catchment hydrological processes. This study aims to characterize typical hillslope soil type responses through inferring qualitative hillslope descriptions into a numerical catchment scale model allowing for lateral subsurface routing between adjacent soil horizons. Hydrometric and tracer observation are used to describe and quantify dominant hillslope hydrological processes. Simplifications of hillslope process descriptions are used to calibrate the model to represent the subsurface hillslope connectivity. Results show that hillslope scale hydrological process characteristics can be faithfully simulated with quaternary scale climate, land use and soils data, discriminating only between different hillslope soil types. The simplification of hillslope soils into three distinct groups allows for the further derivation of dimensionless descriptors of hillslope hydrological response using the Advection Dispersion Function. Slopes with shallower stratified soils showed rapid responses to rainfall in the soil water, while those with deeper soils and less horizontal stratification showed appreciably slower responses to rainfall, with older hillslope water dominating soil water for longer periods. This identifies soils as a dominant determinant in hillslope runoff characteristics. This allows for the characterization and ultimately a simplified classification of different hillslope soils and their response types, which is applicable at a range of scales. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.

To meet society’s needs for water, food, fuel and fibre the natural land cover throughout the world has been extensively altered. These alterations have impacted on hydrological responses and thus on available water resources, as the hydrological responses of a catchment are dependent upon, and sensitive to, changes in the land use. Similarly, changes in the climate through enhanced carbon dioxide (CO2) levels in the atmosphere have resulted in increased temperature and altered precipitation patterns that alter hydrological responses. In combination, land use change and global climate change form a complex and interactive system, whereby both human influences and climate change manipulate land use patterns, and changes in land uses feed back to influence the climate system, with both impacting on hydrological responses. Relatively few studies have been undertaken examining the combined impacts of climate change and land use change on water resources, with no consensus emerging as yet as to combined influence of land use change and climate change on hydrological responses and the role of geographical characteristics in determining the overriding influence. There is, however, agreement that the effect on hydrological responses will be amplified. Given that South Africa is currently water stressed and considered to be highly exposed to climate change impacts, an understanding of hydrological responses to the complex interactions between land use and climate change is crucial to allow for improved integration of land use planning in conjunction with climate change adaptation into water resources management. To determine the sensitivity of land use to changing climate, a sensitivity study assessing the potential impacts of climate change on the areas climatically suitable for key plantation forestry species was undertaken. Under sensitivity scenarios of climate change the climatically optimum areas for specific forest species were shown to shift, with optimum areas changing in extent and location between and within South Africa’s provinces. With potential for shifts in land use due to climate change shown, the imperative to improve understanding of the dynamics between land use and climate change as well as the subsequent impacts on hydrological responses was further established. For the assessment of climate-land use-water interactions, a process-based hydrological model, sensitive to land use and climate, and changes thereof, viz. the daily time step ACRU model was selected. In order to increase the confidence in results from the model in a study such as this, its representation of reality was confirmed by comparing simulated streamflow output against observations across a range of climatic conditions and land uses. This comparison was undertaken in the three diverse South African catchments chosen for the study, viz. the semi-arid, sub-tropical Luvuvhu catchment in the north of the country, which has a large proportion of subsistence agriculture and informal residential areas, the Upper Breede catchment in the winter rainfall regions of the south, where the primary land uses are commercial orchards and vineyards, and the sub-humid Mgeni catchment along the eastern seaboard, where plantation forestry is dominant in the upper reaches, commercial plantation sugarcane and urban areas in the middle reaches, and urban areas dominate the lower reaches. Thus, in effect a space for time study was undertaken, thereby reducing the uncertainty of the model’s ability to cope with the projected future climate scenarios. Overall the ACRU model was able to represent the high, low and total flows, and thus it was concluded that the model could be used with confidence to simulate the streamflows of the three selected catchments and was able to represent the hydrological responses from the range of climates and diversity of land uses present within the catchments. With the suitability of the model established for the theme of this research, the understanding of the complex interactions between hydrological responses and land use could be improved. The hydrological responses of the three selected catchments to land use change were varied. Results showed that the location of specific land uses within a catchment plays an important role in the response of the streamflow of the catchment to that land use change. Furthermore, it was shown that the contributions of different land uses to the streamflow generated from a catchment are not proportional to the relative area of those land uses, and the relative contribution of the land use to the catchment streamflow varies with the annual rainfall of the catchment. With an improved understanding of the dynamics between land uses and hydrological responses, the impacts of climate change on hydrological responses were assessed prior to analysing the combined impacts on land use and climate change. Five plausible climate projections from three coupled atmosphere-ocean global climate models covering three SRES emissions scenarios which were downscaled with the RCA3 regional climate model and adjusted using the distribution-based scaling (DBS) approach for bias correction were used as climate input to the ACRU model, with future projections applied to a baseline land cover scenario compared to historical climate applied to the same baseline land cover scenario. No consistent direction of change in the streamflow responses was evident in the Mgeni and Luvuvhu catchments. However, decreases in streamflow responses were evident for all five scenarios for the Upper Breede. With an understanding of the separate impacts of land use and climate change on hydrological responses, an analysis of the combined impacts was undertaken to determine which changes were projected to be of greater importance in different geographical locations. Results indicated that the drier the climate becomes, the relatively more significant the role of land use becomes, as its impact becomes relatively greater. The impacts of combined land use and climate change on the catchments’ streamflow responses varied across both the temporal and spatial scales, with the nature of the land use and the magnitude of the projected climate change having significant impacts on the streamflow responses. From the research undertaken, the key results were • that the climatic variable to which plantation forestry species are most sensitive is rainfall; • that optimum growth areas for plantation forestry are projected to shift under changing climates, having a potentially significant impact on the landscape and thus on the hydrological responses from the landscape; • that the daily time-step, physical-conceptual and process-based ACRU model is appropriate for use in land use change and climatic change impact studies as shown through a space for time study; • that the contributions of different land uses to the streamflow generated from a catchment is not proportional to the relative area of that land use and that, as the mean annual precipitation of a subcatchment decreases, so the disparities between the relative areas a land use occupies and its contribution to catchment streamflow increases; • that specific land use changes have a greater impact on different components of the hydrological response of a catchment; • that land uses which currently have significant impacts on catchment water resources will place proportionally greater impacts on the catchment’s water resources if the climate were to become drier; thus the drier the climate becomes, the more relatively significant the role of land use becomes; • that when considering any hydrological impacts of land use change, climate change or combined land use and climate change, assessments need to consider the scale where the localized impacts may be evident, the progression of the impacts as the streamflow cascades through the catchment, as well as the impacts at the whole catchment scale where the accumulation of the effects through the catchment are evident; and lastly • that each catchment is unique with its own complexities, feed forwards and feedbacks, thus each catchment will have a unique threshold as to where land use change or climate change begins to have a significant influence of the hydrological response. Given these complex interactions between land use, climate and water, there is a growing imperative to improve the understanding of the movement of water within catchments, to be receptive and adaptive to new concepts and information, and to developing resilient and adaptive water management strategies for the future in a way that minimises the risks and maximises the benefits to potential impacts of climate change. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

The past few decades have seen, amongst other topical environmental issues, increased concerns regarding the imminent threat of global warming and the consequential impacts of climate change on environmental, social and economic systems. Numerous groundbreaking studies conducted independently and cooperatively have provided abundant and conclusive evidence that global climates are changing and that these changes will almost certainly impact natural and socio-economic systems. Increased global change pressures, which include, inter alia, climate change, have increased concerns over the supply of adequate quality freshwater. There is an inadequate body of knowledge pertaining to linking basic hydrological processes which drive water quality (WQ) variability with projected climate change. Incorporating such research into policy development and governance with the intention of developing adaptive WQ management strategies is also overlooked. Thus, the aim of this study was the assessment of projected climate change impacts on selected WQ constituents in the context of agricultural non-point source pollution and the development of the necessary adaptation strategies that can be incorporated into WQ management, policy development and governance. This assessment was carried out in the form of a case study in the Mkabela Catchment near Wartburg in KwaZulu-Natal, South Africa. The research involved applying climate change projections derived from seven downscaled Global Circulation Models (GCMs) used in the Fourth Intergovernmental Panel on Climate Change (IPCC) Assessment Report, in the ACRU-NPS water quality model to assess the potential impacts on selected water quality constituents (viz. sediment, nitrogen and phosphorus). Results indicated positive correlations between WQ related impacts and contaminant migration as generated from agricultural fertilizer applications. ACRU-NPS simulations indicated increases in runoff and associated changes in WQ variable generation and migration from upstream sources in response to downscaled GCM projections. However, there was limited agreement found between the simulations derived from the various downscaled GCM projections in regard to the magnitude and direction (i.e. percent changes between present and the future) of these changes in WQ variables. The rainfall distribution analyses conducted on a daily time-step resolution for each selected GCM also showed limited consistency between the GCM projections regarding rainfall changes between the present and the future. The implication was that since hydrological and climate change modelling can inform adaptation under climate change. However, adaptation to climate change in water quality management and policy development is going to require approaches that fully recognise the uncertainties presented by climate change and the associated modelling thereof. It was also considered crucial that equal attention be given to both climate change and natural variability, in order to ensure that adaptation strategies remain robust and effective under conditions of climate change and its respective uncertainties. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.

Nature provides essential services to humans, including climate regulation, water provisioning and regulation. These so-called ecosystem services have economical, societal and environmental value. This research aims at improving the knowledge on the linkages between selected hydrological ecosystem services and current and proposed land uses within the water-limited Mpushini/Mkhondeni Catchments in South Africa. The research contributes to the recognition of feedback and linkages within the complex ecological-human system, so that informed land use decisions can be made. The research aim is achieved by first reviewing the literature on hydrological ecosystem services, land use in an ecosystem services context and the links between the two. The study area is then sub-delineated into land use determined hydrological response units for baseline natural land cover, as well as for current and proposed land use scenarios. Using an appropriate model, selected hydrological processes are simulated in order to isolate the effects of individual land uses on hydrological responses, both on a local and a more catchment-wide scale. Various land uses were found to affect hydrological responses, such as runoff and its components of stormflows and baseflows, as well as transpiration and sediment yields, differently. These responses were found to be suitable indicators of selected ecosystem services such as water provisioning or flow regulation. Irrigation and high biomass crops, such as sugarcane and wattle plantations were found to reduce downstream water provisioning services. Degraded lands were found to reduce physical water quality through increased sediment yield, to reduce water provisioning during low flow periods, while the degraded lands increased stormflows, thereby reducing regulation of high flows. Urban land uses were found to significantly increase runoff, with increased impervious areas causing a shift from evaporation and transpiration towards runoff. Stormflows increased, with high flow regulation being reduced. Baseflows increased as well, as a result of a spill-over of runoff from impervious to pervious urban areas, which led to increased low flow regulation. In addition, in this study area urban return flows are generated from externally sourced water, further increasing streamflows and especially low flows. While urban areas showed an increase in downstream water quantity provision, the water quality was reduced. The combined effects of the current land use mosaic on the annual streamflows partially cancel each other out, while the proposed urbanisation dominated hydrological responses. Influences of various land uses on hydrological ecosystem services were thereby shown, which contributes to a better understanding of the linkages between the two. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2014.

Natural vegetation has been converted to land uses, such as agriculture, commercial forestry and urban use, to meet increasing human demands for food, fuel and shelter. These land use changes modify the surface conditions of an area, resulting in changes in hydrological responses. Urban land use, in particular, has a significant impact on catchment hydrology as a result of the increased impervious areas such as concrete, tar and roofs. To assess the future hydrological impacts of urban land use, the scale and location of future urban areas must be considered. The objective of this study was to assess the hydrological responses to future urban growth in the Mgeni catchment, South Africa. An urban growth model was used to generate scenarios of plausible future urban growth and these scenarios were modelled using a hydrological model to determine the hydrological responses to urban growth. The plausible future urban growth in the Mgeni catchment was modelled using the SLEUTH Urban Growth model (SLEUTH). The SLEUTH acronym stands for the input layers required for the model viz. Slope, Land use, Excluded areas, Urban Extent, Transport routes and Hillshade. SLEUTH is able to provide the scale and location of future urban growth required to assess the hydrological impacts of future urban growth. The data requirements and modelling procedure for SLEUTH is relatively simply and therefore it is well suited to a South African context. SLEUTH was calibrated and applied to the Mgeni catchment to project future urban land use. When assessing the 95-100% probability class, the results revealed that the Henley, Pietermaritzburg and Durban areas would experience the highest urban growth in the Mgeni catchment by the year 2050. The outputs of the SLEUTH Model for the Mgeni catchment showed a number of similarities to another application of SLEUTH in Cape Town. These similarities indicate the SLEUTH performs in a similar way for the two South African cities. Therefore, it was concluded that the SLEUTH Model is suitable to account for urban growth in the Mgeni catchment, as required for use in hydrological impact studies. The hydrological responses to urban growth in the Mgeni catchment were assessed using the ACRU model. The scenarios of plausible future urban growth generated by SLEUTH were overlaid with current land cover layers to generate maps of plausible future urban land use. The results showed extensive urban growth of >95% probability occurring in the Midmar, Albert Falls, Henley, Pietermaritzburg, Table Mountain, Inanda and Durban Water Management Areas (WMAs) by 2050. Increases in mean annual streamflows were observed in many of these areas; however the Henley, Pietermaritzburg and Table Mountain WMAs were shown to have greater increases in mean annual streamflow than the other areas that showed similar increases in urban growth, thus indicating that these WMAs could be particularly responsive to urban growth in the future. Furthermore, the results showed that the type of urban land use is important in determining the hydrological responses of urban land use, as the imperviousness differs between the different urban land uses. Streamflow responses were shown to be influenced by the scale and location of urban growth in the Mgeni catchment and specific areas, such as the WMAs along the Msunduzi River, were identified as potentially responsive to urban growth. Summer streamflows were indicated as being more responsive to urban land use changes than winter streamflows and increases in streamflows due to urban growth start to over-ride the impacts of other land uses which have substantial impacts on hydrological responses such as commercial forestry, and commercial sugarcane by 2050, whereas in other areas increases were mitigated by the presence of major dams. Lastly, it was shown that the type of urban land use, such as built up urban areas when compared to informal urban areas for example, have a significant impact on streamflow responses. These results are useful as they can be used to inform both water resources planning as well as urban planning to ensure that South Africa’s valuable water resources are protected. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.