Lau Ka Wah Joyce. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 177-192). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.iv / Table of Contents --- p.vi / List of Tables --- p.xi / List of Figures --- p.xiv / List of Plates --- p.xvi / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.1.1 --- Environment of Hong Kong --- p.1 / Chapter 1.1.1.1 --- Topography --- p.1 / Chapter 1.1.1.2 --- Climate --- p.1 / Chapter 1.1.1.3 --- Expanding population --- p.3 / Chapter 1.1.2 --- Landslide history in Hong Kong and government action --- p.4 / Chapter 1.1.3 --- Slopes in Hong Kong --- p.6 / Chapter 1.1.4 --- Stabilization means --- p.7 / Chapter 1.2 --- Biotechnical stabilization --- p.8 / Chapter 1.2.1 --- Concept --- p.8 / Chapter 1.2.2 --- History --- p.9 / Chapter 1.2.3 --- Advantages and strengths of vegetation --- p.9 / Chapter 1.2.4 --- Other components in biotechnical stabilization --- p.11 / Chapter 1.3 --- The situation in Hong Kong --- p.12 / Chapter 1.3.1 --- Government policy on control of visual impact of slopes --- p.12 / Chapter 1.3.2 --- Landslip Preventive Measures (LPM) Program --- p.15 / Chapter 1.3.3 --- Slope landscaping proprietary systems --- p.16 / Chapter 1.3.3.1 --- Proprietary systems --- p.16 / Chapter 1.3.3.2 --- Problems and limitations --- p.20 / Chapter 1.4 --- Ecosystem reconstruction on slopes --- p.23 / Chapter 1.4.1 --- Concept --- p.23 / Chapter 1.4.2 --- Plant requirements --- p.24 / Chapter 1.4.3 --- Potential challenges --- p.24 / Chapter 1.4.3.1 --- Steep gradient and related problems --- p.24 / Chapter 1.4.3.2 --- Thin soil --- p.24 / Chapter 1.4.3.3 --- Water supply --- p.26 / Chapter 1.4.3.4 --- Nutrient availability --- p.27 / Chapter 1.5 --- Species selection --- p.28 / Chapter 1.5.1 --- Vegetation types --- p.28 / Chapter 1.5.2 --- Natives or exotics --- p.29 / Chapter 1.5.3 --- Currently employed species and problems --- p.29 / Chapter 1.6 --- The current study --- p.31 / Chapter 1.6.1 --- Objectives --- p.31 / Chapter 1.6.2 --- Significance --- p.31 / Chapter Chapter 2 --- Soil status and vegetation of cutslopes --- p.35 / Chapter 2.1 --- Introduction --- p.35 / Chapter 2.2 --- Materials and methods --- p.42 / Chapter 2.2.1 --- Physical properties of substrates on slopes --- p.43 / Chapter 2.2.1.1 --- Gradient --- p.43 / Chapter 2.2.1.2 --- Aspect --- p.43 / Chapter 2.2.1.3 --- Soil depth --- p.44 / Chapter 2.2.1.4 --- Bulk density --- p.44 / Chapter 2.2.1.5 --- Soil texture --- p.44 / Chapter 2.2.2 --- Chemical properties of substrates on slopes --- p.45 / Chapter 2.2.2.1 --- pH --- p.45 / Chapter 2.2.2.2 --- Conductivity --- p.45 / Chapter 2.2.2.3 --- Organic carbon --- p.46 / Chapter 2.2.2.4 --- Carbon: nitrogen ratio --- p.46 / Chapter 2.2.2.5 --- Total Kjeldahl Nitrogen --- p.46 / Chapter 2.2.2.6 --- Mineral nitrogen (Ammonium and nitrate) --- p.46 / Chapter 2.2.2.7 --- Total phosphorus --- p.47 / Chapter 2.2.2.8 --- Available phosphorus --- p.47 / Chapter 2.2.2.9 --- Major extractable cations --- p.47 / Chapter 2.2.3 --- Statistical analysis --- p.47 / Chapter 2.2.4 --- Other properties on slopes --- p.48 / Chapter 2.2.4.1 --- Green coverage --- p.48 / Chapter 2.2.4.2 --- Invaded species --- p.48 / Chapter 2.3 --- Results --- p.48 / Chapter 2.3.1 --- Physical properties of substrates on slopes --- p.48 / Chapter 2.3.2 --- Chemical properties of substrates on slopes --- p.51 / Chapter 2.3.3 --- Other properties of the slopes --- p.58 / Chapter 2.3.3.1 --- Green coverage --- p.58 / Chapter 2.3.3.2 --- Invaded species --- p.60 / Chapter 2.4 --- Discussion --- p.61 / Chapter 2.4.1 --- The physical properties of substrates on slopes --- p.63 / Chapter 2.4.2 --- Chemical properties of substrates and their seasonal changes on slopes --- p.66 / Chapter 2.4.3 --- Green coverage and its seasonal changes --- p.70 / Chapter 2.4.4 --- Comparison between the standards and results --- p.75 / Chapter 2.4.5 --- Other problems --- p.78 / Chapter 2.5 --- Summary --- p.79 / Chapter Chapter 3 --- Species selection for cutslope revegetation --- p.81 / Chapter 3.1 --- Introduction --- p.81 / Chapter 3.1.1 --- The need to expand species variety for revegetation --- p.81 / Chapter 3.1.2 --- Criteria for plant selection --- p.81 / Chapter 3.1.3 --- Advantages of grasses and herbaceous legumes --- p.83 / Chapter 3.1.4 --- Pot experiment --- p.85 / Chapter 3.2 --- Materials and methods --- p.86 / Chapter 3.2.1 --- Summer grasses --- p.88 / Chapter 3.2.1.1 --- Germination rate --- p.88 / Chapter 3.2.1.2 --- Pot experiment --- p.88 / Chapter 3.2.2 --- Summer legumes --- p.90 / Chapter 3.2.3 --- Winter grasses --- p.90 / Chapter 3.2.4 --- Winter legumes --- p.90 / Chapter 3.3 --- Results --- p.91 / Chapter 3.3.1 --- Soil properties --- p.91 / Chapter 3.3.2 --- Aboveground biomass production --- p.91 / Chapter 3.3.2.1 --- Summer grasses --- p.91 / Chapter 3.3.2.2 --- Summer legumes --- p.98 / Chapter 3.3.2.3 --- Winter grasses --- p.101 / Chapter 3.3.2.4 --- Winter legumes --- p.106 / Chapter 3.3.3 --- Foliar nutrient concentration --- p.111 / Chapter 3.3.3.1 --- Summer grass --- p.111 / Chapter 3.3.3.2 --- Summer legumes --- p.113 / Chapter 3.3.3.3 --- Winter grasses --- p.114 / Chapter 3.3.3.4 --- Winter legumes --- p.115 / Chapter 3.4 --- Discussion --- p.116 / Chapter 3.4.1 --- Aboveground biomass production --- p.119 / Chapter 3.4.1.1 --- Summer grasses --- p.119 / Chapter 3.4.1.2 --- Summer legumes --- p.121 / Chapter 3.4.1.3 --- Winter grasses --- p.122 / Chapter 3.4.1.4 --- Winter legumes --- p.125 / Chapter 3.4.2 --- Foliar nutrient concentration --- p.126 / Chapter 3.4.3 --- Common nutrient application and the plant requirements --- p.128 / Chapter 3.5 --- Summary --- p.129 / Chapter Chapter 4 --- Growth of summer grasses in a combination of stresses --- p.131 / Chapter 4.1 --- Introduction --- p.131 / Chapter 4.2 --- Materials and methods --- p.131 / Chapter 4.2.1 --- Study species --- p.131 / Chapter 4.2.2 --- Pot experiment --- p.132 / Chapter 4.3 --- Results --- p.132 / Chapter 4.3.1 --- Pot experiment --- p.132 / Chapter 4.3.1.1 --- Aboveground biomass --- p.132 / Chapter 4.3.1.2 --- Foliar nutrient concentration --- p.138 / Chapter 4.4 --- Discussion --- p.140 / Chapter 4.4.1 --- Pot experiment --- p.140 / Chapter 4.4.1.1 --- Aboveground biomass --- p.140 / Chapter 4.4.1.2 --- Foliar nutrient concentration --- p.141 / Chapter 4.5 --- Summary --- p.141 / Chapter Chapter 5 --- Growth of summer grasses on simulated slopes --- p.143 / Chapter 5.1 --- Introduction --- p.143 / Chapter 5.2 --- Materials and methods --- p.145 / Chapter 5.2.1 --- Study species --- p.145 / Chapter 5.2.2 --- Artificial panel trial --- p.145 / Chapter 5.2.2.1 --- Experimental setup --- p.145 / Chapter 5.2.2.2 --- Growth pattern and green coverage --- p.147 / Chapter 5.2.2.3 --- Sediment runoff and change in soil thickness --- p.147 / Chapter 5.3 --- Results --- p.148 / Chapter 5.3.1 --- Grass growth on artificial panels --- p.148 / Chapter 5.3.1.1 --- Aboveground biomass and green coverage --- p.148 / Chapter 5.3.2 --- "Relationship between rainfall, runoff and soil loss" --- p.149 / Chapter 5.3.2.1 --- Effect of rainfall on runoff --- p.149 / Chapter 5.3.2.2 --- Effect of runoff on soil loss --- p.151 / Chapter 5.3.2.3 --- Effect of rainfall on soil loss --- p.152 / Chapter 5.3.2.4 --- Effect of aspect --- p.154 / Chapter 5.3.2.5 --- Effect of green coverage on soil loss --- p.154 / Chapter 5.3.3 --- Percentage of greening --- p.155 / Chapter 5.3.4 --- Soil thickness --- p.157 / Chapter 5.4 --- Discussion --- p.159 / Chapter 5.4.1 --- Grass growth on artificial panels --- p.159 / Chapter 5.4.2 --- "Relationship between rainfall, runoff and soil loss" --- p.160 / Chapter 5.4.2.1 --- Effect of rainfall on runoff --- p.160 / Chapter 5.4.2.2 --- Effect of runoff on soil loss --- p.160 / Chapter 5.4.2.3 --- Effect of rainfall on soil loss --- p.161 / Chapter 5.4.2.4 --- Effect of aspect on runoff and soil loss --- p.163 / Chapter 5.4.2.5 --- Effect of green coverage on runoff and soil loss --- p.164 / Chapter 5.4.3 --- Effects of other variables --- p.165 / Chapter 5.4.3.1 --- Effect of green coverage --- p.165 / Chapter 5.4.3.2 --- Effect of aspect --- p.167 / Chapter 5.4.4 --- Soil thickness --- p.168 / Chapter 5.5 --- Summary --- p.168 / Chapter Chapter 6 --- Conclusion --- p.170 / Chapter 6.1 --- Summary of major finding --- p.170 / Chapter 6.2 --- Implications of the study --- p.172 / Chapter 6.2.1 --- Growth medium --- p.172 / Chapter 6.2.2 --- Species selection --- p.174 / Chapter 6.3 --- Limitations of the study --- p.175 / Chapter 6.4 --- Suggestions for further investigation --- p.175 / References --- p.177

Rainier, Oregon, has experienced problems in the development of residential and commercial sites, utilities, and transportation facilities as a result of slope instability. This study of slope stability at Rainier was conducted at the request of city officials.

published_or_final_version / Applied Geosciences / Master / Master of Science

published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

Previous studies found that during a rainfall event, pre-event water, which exists in the catchment before the event, may appear in significant amounts in the stream stormflow hydrograph. Pre-event water is predominantly groundwater. Among the mechanisms that have been proposed to explain the rapid mobilization of pre-event water from hillslopes are: (1) groundwater ridging (GWR) i.e. the rapid rise of a water table in environments, where the capillary fringe, or the zone of tension saturation, is very close to the ground surface and (2) the Lisse Effect (LE) i.e. the rapid response of a groundwater level to pressurized pore air in the unsaturated zone. Published literature explains that GWR is caused by the application of a small amount of water on the ground surface. On the LE, it is explained that pressurized pore air acts at the water table, resulting in a rapid rise of the water level in a well, screened below the water table. These explanations are insufficient on the physical processes involved in GWR and the LE. The objectives of this study were: (1) to use the commonly observed catchment hydrological processes i.e. tensiometric pore water pressure, shallow groundwater levels, rainfall data and the hydraulic properties of soils, to quantify and describe the physical processes involved in GWR and the LE mechanisms; (2) to perform laboratory experiments, in order to understand the physical processes involved in the LE; and (3) to develop a mathematical theory that can describe the physical processes in the LE. Results indicated that GWR and the LE are caused by the addition (elevation) of potential energy in water within the capillary fringe. In GWR, the additional energy is from the intense rainfall. In the LE, the additional energy is from compressed pore air in the unsaturated zone. In both mechanisms, the added energy diffuses through the capillary fringe, as a downward pressure wave, releasing the tension forces in water. As soon as the downward pressure wave-front arrives at the water table, the water table begins to ascend, as an upward pressure wave. The ascending water table steepens the hydraulic gradient, which results in the rapid groundwater fluxes, without the recharge of the water table by the infiltration profile. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2013.

Hillslope mechanisms and processes are a complex and dynamic set of interactions, but are nevertheless vital components of hydrology due to their critical interactions with surface and groundwater (Lorentz, 2001a). In order to observe and quantify these flow generating mechanisms, the Weatherley subcatchment was selected where the components of streamflow generation have been studied and can be quantified separately. Surface, shallow subsurface and the deeper groundwater interactions are particularly important when quantifying runoff generation from within hillslope, riparian and wetland zones as they are the dominant runoff generating zones within the Weatherley catchment. These components of flow are important to quantify for the further study of flow generation mechanisms, their dynamics and fluxes at the hillslope and small catchment scale, low flow contributions, climate change as well as the consequences of land use change (Lorentz, 2001b). Transfer functions were found to be the best adaptation of hydrograph separation for distributed hydrological modelling purposes when attempting to quantify the various streamflow hydrograph components. In this study, the runoff components were simulated along transects using the HYDRUS-2D model, where the simulated soil water dynamics are compared with the observed tensions and water contents at different depths within the soil profile in order to quantify the contributing hillslope fluxes to streamflow generation. The 2001 data set was used with the rainfall and potential evapotranspiration data being converted into rates according to the breakpoint rainfall data. The HYDRUS-2D modelling exercise is performed to calculate the variety of flux rates (timing and quantities) within the subcatchment, so that the overall stream hydrograph can be properly deduced when modelling this catchment with transfer functions in the future. An understanding of the driving forces as well as the behaviour of sources and flow paths was extracted from this thesis, along with gaining some knowledge about the mechanisms and behaviour of streamflow generating mechanisms at the hillslope and small catchment scale. Troch et al (2003) clearly encapsulates the essence of modern day catchment hydrology in stating that hillslope response to rainfall remains one of the most central problems of catchment hydrology in order to quantify catchment responses. The processes whereby rainfall becomes runoff continue to be difficult to quantify and conceptualise (Uhlenbrook et al., 2003) and this is because the characterisation of subsurface water flow components is one of the most complex and challenging tasks in the study of the hydrologic cycle (Achet et al., 2002). Since trying to understand the temporal and spatial variability of moisture content and the subsurface flow mechanisms is a complicated problem (Achet et al., 2002), an attempt is made in this thesis to gain insights into the temporal and spatial variability of soil tensions and soil moisture content at various depths on hillslope transects by combining modelling exercises with field observations. From this modelling, the hillslope water balance and contributing fluxes are derived in effort to augment, at a later stage, the hillslope response functions. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

Several hydrological studies claim that available water resources in a catchment are affected by large scale afforestation, especially where the regional rainfall is considered marginal for the support of silviculture. Nevertheless, the mechanisms and magnitude of the perturbations to the receiving water resources due to afforestation are still not clearly understood. To improve this understanding an intensive hydrological experiment has been initiated in the small grassed Weatherly catchment of the Mondi, North East Cape Forests. Details of the soil water dynamics on the Molteno formations in the catchment have been be studied. This research presents a description and first results of the establishment of an experiment which comprises monitoring the water budget of the grassed catchment prior to the afforestation of the catchment to plantations of exotic trees. The studies currently include, monitoring the infiltration and redistribution of soil water on a hillslope as well as monitoring of interflow mechanisms and localised mechanisms of soil water accumulation influenced by the topography and geology of the catchment. In addition to the intensive soil water monitoring, specific experimentation has been conducted at various locations on the hillslope. These comprise macropore flow process studies and 2-dimensional tracer experiments. Details of these experiments as well as the automated soil water and groundwater monitoring instrumentation are presented. An intensive soil survey on a 30 m x 30 m grid as well as a comprehensive measurement strategy of soil physical and hydraulic properties are highlighted. A review of 2-dimensional numerical hillslope soil water process models is also presented. Results from this research show that on hillslopes underlain by Molteno sandstones localised perched water tables form. These water bodies, upon reaching a critical height above the bedrock cascade downslope as interflow recharging the water bodies downslope. The response to infiltration increases downslope and in the toe region interflow occurs readily in response to rainfall compared to the midslope where substantial rain needs to infiltrate. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1997.

Terracettes are a widely occurring form of micro-relief found throughout regions displaying various climatic and environmental conditions. Much speculation surrounds the processes responsible for their formation and development. An investigation of these micro-forms, their associated soil physical properties, sustaining mechanisms, and their relationship to slope stability was undertaken in Giant's Castle Game Reserve, KwaZulu - Natal Drakensberg, South Africa. The study showed that relationships between terracette morphology and soil physical properties within the Reserve are few, and that current soil conditions cannot be used to infer process related to terracette formation. However dry bulk density data indicated that soil creep is the dominant formative mechanism within the Reserve. Throughflow at riser surfaces was the dominant sustaining mechanism, with needle ice growth, wind, surfacewash and animal disturbance contributing minor retreat at both treads and risers. Aspect played an important role in determining soil physical characteristics. It was inferred that terracettes imparted stability to the slopes on which they are found, and with continued retreat at both treads and risers the slope was again placed under conditions of instability. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1998.

Tree-rings were analyzed to assess the relative importance of slope position and aspect as determinants of the climate-sensitivity of sugar maple and white oak radial growth. Tree size, crown condition, forest and soil composition, and site indices were assessed to document environmental differences between site-types and to verify similarity of stands within the same site-type. Climate-sensitivity was assessed using mean between-tree correlation, principal components analysis, mean sensitivity, regression analysis, and analysis of radial growth decline after severe drought. Ecological differences were found between high and low sites on north and south facing aspects. Sugar maple did not exhibit greater climate-sensitivity than white oak. Both species showed greater climate-sensitivity on upper and south-facing slopes. / Department of Biology

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.