It is now widely believed that globally averaged temperatures will rise significantly over the next 100 years as a result of increasing atmospheric concentrations of greenhouse gases (GHG) such as carbon dioxide. Responses to the threat of future climate change are both adaptations to new climate conditions, and mitigation of the magnitude of change. Mitigation can be achieved both through reducing emissions of greenhouse gases and by increasing storage of carbon in the earth system. In particular it is thought that there is potential for increased storage of carbon on land in soils and growing vegetation. There is now a need for research on the potential impacts of changing land use on terrestrial carbon storage, in particular as rapid land use and land cover change has taken place in most of regions of world over the past few decades due to accelerated industrialization, urbanization and agricultural practice. This thesis has developed a novel methodology for estimating the impacts of land use and land cover change (LULCC) on terrestrial carbon storage using Geographic Information Systems and Optimization modelling, using a regional case study (the Tamar Valley Catchment, southwest England) and drawing entirely on secondary data sources (current distributions of soils and vegetation). A series of scenarios for future land cover change have been developed, for which carbon storage, GHG and energy emissions amount have been calculated over the short, medium and long term (2020, 2050 and 2080). Results show that in this region, improving permanent grassland and expanding forestry land are the best options for increasing carbon storage in soils and biomass. The model has been validated using sensitivity analysis, which demonstrates that although there is uncertainty within the input parameters, the results remain significant when this is modelled within the linear programme. The methodology proposed here has the potential to make an important contribution to assessing the impacts of policies relating to land use at the preparation and formulation stages, and is applicable in any geographic situation where the appropriate secondary data sources are available.

Water availability in Southern Africa is highly variable both in time and space, thereby exposing the region to high risks in water availability. This is further compounded by numerous human activities which have significant impact on water resources. The brunt of the risks associated with water scarcity is particularly heaviest on resourceconstrained farmers who depend largely on rain-fed agriculture for subsistence. With continuously increasing demands on the water resources, the need for a better understanding of the hydrological systems becomes crucial as it forms the gateway for providing reliable information for managing water resources. It is also increasingly becoming more important to address land and water linkages because land use decisions are water use decisions. Operational hydrology provides an insight into the effects of man-made changes, the foreseeable hydrological characteristics at a given site, and the long-term prediction of the future hydrological effects of human activities. This provides for a more holistic approach in managing land and water resources as well as the impact of land use on partitioning rainfall into streamflow. This report discusses the application of the SWAT model to the B72E - F quaternary catchments in the Olifants Water Management Area to assess streamflow generation and the effects of human-environment interactions on the hydrology. Results show an expected correlation between land cover and the hydrologic response where an increase in land cover corresponds to a reduction in the streamflow. Range grass shows a higher reduction in the streamflow followed by forestry with arid land giving the highest increase in streamflow. Prediction in the similar neighbouring and ungauged B72A catchment gives a MAR of 68mm. Additionally, a rigorous analysis of the concepts of a local hydrological model, HDAM, is done with respect to rainfall which is the main driver of the model. Modifications of some of the relationships used in the model are suggested with the potential of streamlining the model and making it more applicable in the region.

Permafrost is a strongly controlling factor on Arctic hydrology due to its effect on ground permeability, and thus surface and ground water flow paths. As wildfires are increasing in occurrence and magnitude in permafrost regions, they may alter the hydrological regime via permafrost thaw and degradation that increases ground permeability. Thus, it is hypothesized that in permafrost regions catchments exposed to severe wildfire burn may display a river discharge behavior different to that of unburned catchments, with reduced maximum and increased minimum flows corresponding to higher infiltration of precipitation and extended sub-surface flow paths. This study compares the seasonality and magnitude of runoff in severely burned (Odei River) and unburned (Taylor River) catchments in the sporadic permafrost region in the Canadian Shield Taiga. The investigated time span consists of 25 full calendar years with complete daily and monthly river discharge data between 1980 and 2016. They are used in conjunction with burned area data, climate data and landcover data to investigate patterns in hydrology behavior. An emerging trend is a sharply declining maximum flow and increasing minimum flow relative to precipitation in the burned catchment, indicating an accelerated increase in infiltration and buffer capacity of the soil relative to the unburned catchment. Over the entire period the apparent annual catchment storage change is decreasing in both catchments, but at a 115% faster rate in the burned catchment despite being exposed to ~1.5 C lower mean annual temperature, a factor that likely increases the rate of climate-driven aggradation of permafrost in the contrasting unburned catchment. The discrepancy found in catchment streamflow regime between the burned and unburned catchment and its alignment with the suggested permafrost disturbance effects from previous studies suggest that streamflow may serve as a useful and resource efficient indicator of wildfire-driven permafrost degradation.

Magister Artium - MA / Wetlands provide various ecosystem services such as provisioning, regulating, supporting, and cultural services which may be directly or indirectly beneficial to humans. The manner in which such wetlands are managed is partly determined by human perceptions of their value. However, climatic variability and climate change put the continued provision of such ecosystems under stress. The result is that certain ecosystem services may be provided to differing extents during anomalously wet or dry years. There is thus uncertainty as to the values ascribed to wetlands by people during varying climatic phases. This thesis focuses on understanding how people perceive the functioning of wetlands within our current climate against a background of climatic variability and climate change. This study explores people’s perceptions regarding the functioning of wetlands and ecosystem services provided during dry and wet years, as an indication of how climatic variability and climate change impact peoples’ perceptions. The data was collected in the wetlands of the Agulhas Plain in the Nuwejaars Catchment. Five wetlands classified and scored using the WETEcoServices tool. In addition, five semi-structured interviews and three participatory mapping exercises with landowners were also undertaken. The study reports on the landowners’ awareness of wetland ecosystems, ecosystem services and climatic variability and climate change. Provisioning, supporting, and cultural ecosystem services are frequently used by landowners, which can be impacted by climatic variability and climate change. The WETEcoService benefits and landowners perceptions of ecosystem services varies, as the WETEcoService direct and indirect ecosystem services are either effective or ineffective in dry and wet years. In contrast to landowners perceptions emphasising the importance of ecosystem services directly beneficial to them. The study recommends that the ecosystem services landowners perceive as important is linked to their interest to guarantee their participation in catchment management. WET-EcoService benefits can inform landowners and managers about ecosystem services degradation and whether their conservation methods are either positively or negatively impacting wetlands.

>Magister Scientiae - MSc / The Kars has a well-defined channel along the 62 km stretch from its sources in the Bredasdorp Mountains. After entering the Agulhas plain which has a very low gradient, this river changes into a triangular shaped wetland. This wetland is 7 km in length with no defined channel running through it. The wetland then discharges into another 7 km long channel that joins the Heuningnes River with its mouth at the Indian Ocean. The presence of the wetland causes frequent flooding which affects cultivated lands and a major highway linking towns on the coastal Cape Agulhas area with the rest of the country. Before this study, there was no monitoring of flows along the Kars River including water levels within the wetland. Consequently, the conditions leading to flooding of the wetlands were unknown. This study is aimed at understanding how the combination of local rainfall, Kars River inflow into the wetland, soil characteristics, and the morphology of the wetland influence flooding/inundation. The study monitored river inflows into and outflows from the wetland. A soil survey was conducted within the wetland using the augering method and an infiltrometer to determine soil type and infiltration rates. This was done to assess the hydrological characteristics of the wetland. Using the collected climate data and river flow data, a conceptual model was developed for predicting downstream outflows and possible flood events on a daily timescale. The results indicated that the Kars wetland comprises soil with high silt and clay content, and low infiltration capacity. The wetland causes flood attenuation and diffuse surface flows. Low infiltration rates result in ponding of local rainfall which can contribute to flooding.

>Magister Scientiae - MSc / Improved knowledge is required on the quantity and source of water resources, particularly evident during periods of drought currently being faced in South Africa. There is inadequate knowledge with regards to the flood attenuating properties of wetlands, particularly evident in the ungauged catchments of Southern Africa. This study aims to improve the knowledge on the contribution of flow from tributaries with headwaters in mountainous regions to low lying areas and the effects of wetlands on river flow patterns. Several river flow monitoring sites were established along the major upper tributaries of the Nuwejaars River at which daily water levels were recorded and bi-weekly discharge measurements were conducted. Weather data was collected using four automatic weather stations and three automatic rain gauges’ setup throughout the catchment. Rainfall data coupled with rating curves and daily discharges were used to assess the flow responses of these tributaries to rainfall events. Additionally, stable isotope analysis and basic water quality analysis was used to determine the major sources of flow within the major tributaries. The rainfall and river flow data collected, coupled with the characterization of the wetland was used to determine the flood attenuation capabilities of the wetland. Lastly, a conceptual model based on a basic water balance was developed to further explain the role of the wetland and its effects on river flows. The results showed a 27-hour lag time in peak flows from the upper tributaries at the inflows of the wetland to the outflow. Two of the upper tributaries had flow throughout the year and were fed by springs in the upper mountainous regions of the catchment and all tributaries were largely reliant on rainfall for peak flows. The temporary storage of flows within the wetland occurred as a result of the Nuwejaars River bursting its banks, filling of pools, or ponds and the Voëlvlei Lake. It was concluded that the wetland increased the travel time and decreased the magnitude of flows of the Nuwejaars River. However, due to the fact that wetlands are interlinked on a catchment scale and have a collective effect on flood attenuation this study may be improved by looking at the wetlands within the catchment holistically.

University of Technology, Sydney. Faculty of Engineering. / Although extensive worldwide literature on urban stormwater runoff exists, very few publications describe runoff development in terms of its basic building blocks or processes and their individual and accumulative significance in response to varying inputs and boundary conditions. Process algorithms should respond accurately to varying input magnitudes and characteristics as well as to changes in antecedent conditions. The present state of estimation errors involved in many current numerical simulation techniques has been reviewed in this thesis. A significant amount of errors that are presently encountered for have been explained in terms of undefined process response not explicitly included within many modelling methodologies. Extensive field monitoring of intra-catchment rainfall and runoff within an urban catchment at Giralang in Canberra, which is typical of Australian urban catchments, was carried out over a 3-year period to define and measure individual runoff processes. This monitoring work led to a greater understanding of the processes driving the aggregation of local runoff from many sub-areas into the runoff observed at full catchment scale. The results from the monitoring process prompted a number of approaches to potentially reduce standard errors of estimate from model-attributable errors based on improvements to definable catchment response mechanisms. The research isolated a number of basic building blocks associated with typical residential allotments, that can be grouped into roof drainage, yard drainage and adjacent road drainage. A proposed modelling approach was developed that allowed these building blocks at an allotment scale to be simply computed using storage routing techniques. This then aggregated via the total catchment’s public drainage system isochronal characteristics utilising a “process tree” approach to provide full catchment scale runoff response. The potential reduction in estimation errors utilising the developed procedure was assessed using a large number of recorded events from the Giralang catchment monitoring data. The proposed numerical modelling approach was found to provide significant improvements over current methods and offered a scale-independent and stormindependent methodology to model catchments of any size without the need for changes to any of the runoff routing parameters. Additionally the approach permits the flexible sequencing and inclusion of a wide range of different urban drainage structures within a catchment that are representative of the local characteristics. The developed procedure also includes a spatially varied water balance approach to infiltration estimation that is more suited to future continuous simulation models. The developed “flexible process tree” approach provides an important step forward in the numerical modelling of complex urban drainage systems. This can reduce errors of estimate by improving intra-catchment process representation.

Dryland salinity occurs extensively throughout the Spicers Creek Catchment in central west New South Wales, Australia. The extent of dryland salinity in the Spicers Creek Catchment has severely altered the landscape, having major environmental implication. Large area of the catchments has experienced soil erosion resulting from the saline groundwater in the surface soil causing the destruction of clay and soil structure. The objective of this study was to use seismic refraction methods to map in detail a shear zone, which was associated with an area of major dryland salination. In particular, both the width of shear zone and the rock fabric within it were to be mapped with two both compressional (P) and shear (S) waves using a three-dimensional (3D) array of three- component (3C) receivers. The seismic data was recorded across a shear zone which is associated with salination in the Spicers Creek Catchment using the Australian National Seismic Imaging Resources (ANSIR) 360-trace system. Three-component (3C) geophones were used to record shear waves as well as compressional wave. An IVI minivibrator T-15000 was used as the main source of energy for the seismic survey. The results of the three-dimensional three-component seismic refraction surveys at the Spicers Creek Catchment show that the shear zone exhibit the seismic geophysical anomaly of a shear zone, existing as a narrow region with low seismic velocities and increased depth of weathering. A detailed analysis of the refractor seismic velocities and amplitude show a number of linear features parallel to and cross-cutting the shear zone. Linear features cut the shear zones at each site. They have been interpreted as a series of recent faults which act as discharge zone bringing saline groundwater to the surface.

Spicers Creek catchment is located approximately 400 km west of Sydney in the Central West region of New South Wales, Australia. Dryland salinity has been recognised as a major environmental issue impacting soil and water resources in the Central West region of NSW for over 70 years. Due to the geological complexity of the catchment and the presence of high salt loads contained within the soils, groundwater and surface waters, the Spicers Creek catchment was identified as a large contributor of salinity to the Macquarie River catchment. Over fifty-two dryland salinity occurrences have been identified in the Spicers Creek catchment and it appears that dryland salinity is controlled by the presence of geological structures and permeability contrasts in the shallow aquifer system. Combinations of climatic, geological and agricultural factors are escalating salinity problems in the catchment. The main aim of this thesis was to identify the factors affecting salinisation processes in the Spicers Creek catchment. These include the role of geological structures, the source(s) of salts to the groundwater system and the geochemical processes influencing seepage zone development. To achieve these aims a multidisciplinary approach was untaken to understand the soils, geology, hydrogeology and hydrogeochemistry of the catchment. Investigative techniques employed in this project include the use of geophysics, soil chemistry, soil spectroscopy, hydrogeochemistry and environmental isotopes. Evaluation of high-resolution airborne magnetics data showed a major north-east to south-west trending shear zone. This structure dissects the catchment and several other minor faults were observed to be splays off this major structure. These structures were found to be conducive to groundwater flow and are influencing the groundwater chemistry in the fractured aquifer system. Two distinctive groundwater chemical types were identified in the catchment; the saline Na(Mg)-Cl-rich groundwaters associated with the fractured Oakdale Formation and the Na-HCO3-rich groundwaters associated with the intermediate groundwater system. The groundwater chemistry of other deep groundwaters in the catchment appears to be due to mixing between these end-member groundwaters within the fractured bedrock system. The spatial distribution of electrical conductivity, Cl-, Sr2+ and 87Sr/86Sr isotopic ratios showed the correlation between saline groundwaters and the location of faults. Elevated salinities were associated with the location of two crosscutting fault zones. The spatial distribution of HCO3-, K+, Li+ and ?????3CDIC highlighted the extent of Na-HCO3-rich groundwaters in the catchment and showed that these groundwaters are mixing further east than previously envisaged. These findings show that Na(Mg)-Cl-rich groundwaters are geochemically distinctive and have evolved due to extensive water-rock interaction processes within the fracture zones of the Oakdale Formation. These saline groundwaters contain elevated concentrations of trace elements such as As, V and Se, which pose a potential risk for water resources in the area. 87Sr/86Sr isotopic ratios indicated that the source of salinity to the Na(Mg)-Cl-rich groundwaters was not purely from marine or aerosol input. Salt is most likely contributed from various allochthonous and autochthonous sources. This research found that the main mechanism controlling the formation of dryland salinity seepage zones in the Spicers Creek catchment is due to the presence of geological structures. These groundwater seepage zones act as mixing zones for rainfall recharge and deeper groundwaters. The main sources of salt to the seepage zones are from deeper Na(Mg)-Cl-rich groundwaters and rainfall accession. The major importance of this research highlights the need for an integrated approach for the use of various geoscientific techniques in dryland salinity research within geologically complex environments.

Intermittently Closed and Open Lake Lagoons (ICOLLs) are very common along the southern NSW coastline. Expanding urban populations are expanding and these systems are under increasing pressure from anthropogenic activities that change landscape processes and significantly alter the amounts of organic and inorganic constituents entering their waters. Once efficient cycling of nutrients in ICOLLs is overcome, the symptoms of eutrophication establish and the entire ecosystem suffers. These systems have great ecological, social, and economic values that require insightful, well balanced, and educated management to promote sustainable use of these often-sensitive areas. Corunna and Nangudga Lake are ICOLLs in the Eurobodalla Shire on the south coast of NSW. These two ICOLLs receive discharges from catchments covered by native vegetation and grassland. The primary objective of this research component was to quantify catchment exports of total nitrogen (TN), total phosphorus (TP), suspended solids (SS), particulate organic matter (POM) and dissolved organic carbon (DOC) from three small coastal sub catchments that deliver constituents into Corunna and Nangudga Lakes. As part of this investigation the fates of catchment loads in the ICOLLs were established focusing on the lakes water column response to catchment loads and the biogeochemical cycling of nitrogen and phosphorus in sediments.