A baseline study has been undertaken to assess the environmental impact of heavy metals within the fluvial environment of the River Stour, E. Kent, U.K. The occurrence of metal enrichment in surface waters and bed sediments coincides mainly with areas of urbanisation and high density traffic in addition to point source discharges including STW and industrial effluent outlets. Non-tidal surface water samples exhibiting Pb, Co, Cu, Fe and Zn concentrations intermittently elevated above EQS List I and II values largely correspond with bed sediment samples exhibiting metal concentrations above background values and commonly partitioned to the mobile exchangeable/acid soluble and reducible fractions. In the tidal reaches surface water samples exhibiting As, Cd, Co, Cu, Cr, Ni, Pb, V and Zn concentrations above EQS List I and II values are generally associated with bed sediment samples exhibiting partitioning to the immobile oxidisable fraction, suggesting that estuarine processes effectively promote the liberation of elements from the sediment compartment to surface waters. Total catchment annual suspended sediment yield, (190 t/km2/yr), is consistent with previous research work detailing the annual yield of U.K. rivers which in conjunction with suspended sediment concentration data highlights the importance of the transport and distribution of associated elements throughout the river system. Research highlights a requirement to improve point source management measures and control non-point sources and dredging activities and provides an index in which to assess the future impact of anthropogenic sources of metals to the fluvial environment of the River Stour.

A baseline survey of contemporary fluvial sediments in the Kentish Stour, east Kent, England, has been undertaken to document the sources and distribution patterns of anthropogenic PGE in an attempt to constrain some of the physical and chemical parameters that may influence the distribution of these elements. Nine sedimentary rocks, four motorway-runoff sediments and twenty-one river sediments were analysed for PGE by NiS fire assay pre-concentration and ICP-MS. The highest element abundances occur in a sample of ashed sewage sludge (total PGE content of 392 ng/g), whilst the lowest values were recorded in the soils and sedimentary rocks. The total PGE content of the river sediments ranged from 0.4 to 14.2 ng/g in 1999 and from 0.6 to 167 ng/g in 2001, and exhibited significant variation along the river. This variation corresponds strongly with land use changes (urban versus rural) and with points of discharge from sewage treatment works. The PGE and trace element concentrations of the river sediments, sedimentary rocks, motorway runoff sediments and ashed sewage sludge were normalised against their average crustal abundance to identify characteristic normalisation patterns. With this technique, high Pd concentrations in the River Stour sediments were found to be indicative of sewage inputs. The partitioning of Pt, Pd and Rh was investigated in a novel combination of Tessier’s (1979) sequential extraction technique and a Te coprecipitation. The partitioning in the sediments of a sediment retention lagoon progressed from more to less mobile sediment phases. The PGE are emitted in a form (possibly particulate) that becomes predominantly associated with the silicates fraction. The behaviour of the PGE in the River Stour is predicted to be controlled predominantly by physical processes.

Recent research on sediment transport in gravel bed rivers shows evidence of the influence of sub-threshold flow history on values of entrainment thresholds (Paphitis and Collins, 2005; Monteith and Pender, 2005; Haynes and Pender, 2007; Haynes and Ockelford, 2008). The research presented here analyses the effect of the characteristics of hydrograph rising limbs (flow magnitude and duration) on entrainment thresholds of gravel beds, with discharges ranging from 0.25-1.6 times the estimated bed threshold flow and durations from 0.5h to 6h. This analysis uses results from flume experimentation. Entrainment thresholds were determined by two well documented methods: a) particle movement counts (visual method, Yalin, 1977); and b) the reference transport method (RTM) (Parker et al., 1982a; Shvidchenko et al., 2001). Results obtained with near-uniform and uniform bed material sizes show a clear influence of flow magnitude and duration on entrainment thresholds, with bed resistance increasing up to c. 25% for longer durations of antecedent flows when using the visual method, similarly to Paphitis and Collins (2005). The results from the unimodal gravel bed suggest an intermediate duration of rising limb (c. 2h) producing the strongest bed, with more mobile beds resulting from both shorter and longer rising limbs. Total bedload transport rates reduce with increased bed resistance, this effect is also noted during the stability test phase. These results are used to develop a new simplified method for estimating critical bed shear stress using only total bedload data. The performance of a new formulation for bedload rates derived in this thesis is tested against a number of traditional bedload transport equations and appropriately discussed. In-depth analyses of bed surface and bedload size composition and surface grain structure show that bed surface undergoes little change of size composition, with a slightly proportionally larger reduction of fine content, suggesting penetration of fines below the surface. The analysis of coarse-grain bed surface structures, mobility and clustering, based on the size class containing D90 and using digital images taken under UV light, suggests that the surface distribution of coarse grains has a primary role on bed stability.

River ecosystems can be strongly in uenced by contaminants in the water column, in the pore water and attached to sediment particles. Current models [TGD, 2003] predict exposure to sediments based on equilibrium partitioning between dissolved and suspended-particle-sorbed phase in the water column despite numerous studies showing significant direct mass transfer across the sediment water interface. When exchange across the interface (hyporheic exchange) is included in modelling the diffusion coefficient is assumed to be constant with depth. The overall aims of this research were to quantify the vertical variation in diffusion coefficient below the sediment water interface and asses the use of a modified EROSIMESS-System (erosimeter) in the study of hyporheic exchange. The modified erosimeter and novel fibre optic uorometers measuring in-bed concentrations Rhodamine WT were employed in an experimental investigation. Five different diameter glass sphere beds (0.15 to 5.0mm) and five bed shear velocities (0.01 to 0.04m/s) allowed the vertical variation in diffusion coefficient to be quantified to a depth of 0.134m below the sediment water interface. The vertical variation in diffusion coefficient can be described using an exponential function that was found to be consistent for all the parameter combinations tested. This function, combined with the scaling relationship proposed by O'Connor and Harvey [2008] allows a prediction of the diffusion coefficient below the sediment water interface based on bed shear velocity, roughness height and permeability. 1D numerical diffusion model simulations using the exponential function compare favourably with the experimental data.

Diffuse sources of sediment may have important implications for flood risk management (FRM), especially as catchment sediment yields are predicted to increase in future. UK legislation requires FRM to work with natural processes wherever possible, including accounting for sediments. However, the importance of wash-material load to FRM has been under researched and both a robust evidence-base and practical sediment models are needed to identify, prioritise and justify sediment-related catchment management. Research addressing these issues was centred on the River Tone, a sub-catchment of the Parrett, in which features excessive inputs of sediment in its upper catchment combined with high potential for deposition in its lower reaches. Links between sediment sources, water and sediment runoff, and downstream sediment sinks were established and the research examined the role played by sediment, especially wash-material load, within the fluvial system. The greatest sediment-related threats to the functioning of this lowland river stem from either: a protracted, major reduction in wash-material load; or a significant increase in bed-material load. Imbalance in the Tone fluvial-sediment system may not significantly affect flood risk directly, but has implications for FRM operations, maintenance and monitoring. Impacts on land quality result from soil loss. For example, ~2.5 million tonnes of soil has been eroded from the Parrett catchment since WWII. Water quality issues include delivery of phosphate and other pollutants into the river, and potentially more frequent dredging that remobilises contaminants. The thesis defines the key sediment-related components of sustainable, integrated catchment management and provides an improved evidence-base upon which to engage stakeholders. It tests and benchmarks sediment assessment tools including the Sediment Impact Assessment Model (SIAM). An approach to catchment-scale sediment assessment for lowland rivers is recommended, which involves a nested-approach using routinely collected and project-specific field data, stream power screening and SIAM.

The purpose of this study is to analyse the impact of the 2010 Chile earthquake and tsunami on community resilience. Specifically, the thesis examines the role of community resilience in coping with and recovery from natural disasters, and the capacities and external factors that enhance or undermine the levels of community resilience. Furthermore, this study focuses on developing a model suitable for analysing community resilience in the context of natural disasters in Chile. In 2010, a magnitude 8.8 earthquake and tsunami struck Chile. Coastal areas were particularly affected by the disaster; fishing villages were completely destroyed and many people were injured and killed by the tsunami. However, exceptionally, only one fishing village entirely survived the tsunami impact in Talcahuano, one of the worst affected regions by the disaster. This is the case of the ‘El Morro’ community where, despite their boats and houses being swept away by the destructive waves, no one died. This community, considered the most successful experience in coping effectively with the disaster in the country, is the case analysed in this thesis. The results of a primary research conducted in the ‘El Morro’ case study (through methods of semi-structured interviews, observation, informal conversations, documentary review and social media) show that communities have the power to activate internal resources and capacities to cope with and recover from natural disasters. The research highlights that communities are not simply passive victims of disasters; rather, they are active agents. Furthermore, it shows that external factors, specifically political ones can have a detrimental effect on community resilience. Additionally, an integrated model of community resilience was developed which provides new insights into measuring community resilience in the context of natural disasters. Finally, these findings could be useful for designing effective disaster risk reduction programmes and promoting community resilience in Chile and in other developing countries.

Glacial deposits as a whole are some of the most widespread near surface soils in the northern hemisphere, covering large areas of Canada and the United States, eastern and northern Europe and Asia. In Britain during the final Devensian glaciation, significant accretions of stationary ice developed over most upland areas. The resulting materials derived from the attritional action of the base of the moving ice were deposited as till over approximately 60% of the UK. These soils are generally heterogeneous and unsorted, containing varying proportions of clay to boulder size material. This variation in composition has a commensurate effect on the engineering properties of tills. Commercial investigation data from seven sites in Cumbria overlying different bedrock geology were examined in detail using a variety of statistical and graphical techniques to determine whether differences occurred due to bedrock and glacigenic origin. The results of the data analysis confirm the thesis that the bedrock geology, the history of glacigenic deposition and the post glacial history all affect the geotechnical properties of the resulting till. As a corollary, the commonly used empirical relationship between SPT and shear strength used in deriving undrained shear strength was found not to hold for Cumbrian tills.

A reconnaissance survey of the 1000 Km\(^2\) of Masirah Island, Oman, has revealed a fully-developed ophiolite complex which is believed to represent a fragment of Cretaceous ocean crust and upper mantle generated at a constructive plate margin. The complex consists of mantle serpentinites, plutonic rocks ranging from dunite to trondhjemite, a sheeted dyke complex and pillow lava-sediment sequences, all of which have been chemically and petrographically analysed. Several belts of serpentinite occur within the ophiolite associated with major fault-lines. The serpentinites are clearly derived from depleted harzburgitic mantle and their field relations suggest that some were emplaced in the oceanic environment. The chemistry of the plutonic rocks suggests that they are products of dominantly open-system fractional crystallisation of tholeiitic liquid(s), possibly in several discrete magma chambers. Modelling of trace and RE elements suggests that moderate degrees of mantle peridotite melting were involved in production of the magma chamber parental liquid(s). At a higher crustal level sheeted dyke-massive gabbro relationships are interpreted in a model of roof underplating, which causes a decreasing frequency of dyke injection. Metamorphism of the sheeted dykes and lavas is interpreted as sub-sea floor in origin and its effect on whole-rock chemistry is assessed. The dykes and lavas have a chemistry largely typical of present-day ocean tholeiites and the relative contributions of the processes of partial melting and fractional crystallisation to that chemistry are evaluated. Two localised volcanic groups were identified, which appear to have enriched chemistries compatible with origin at off -axis oceanic islands. A major tectonic zone cross-cuts the ophiolite units and has features reminiscent of the modern oceanic transform faults. The importance of this structure, both in the oceanic environment and during the process of ophiolite emplacement, is assessed. Intrusive into the ophiolite is a granite whose trace and RE element chemistry is alien to the oceanic environment and suggests melting of continental crust Finally, a synthesized model of the former constructive margin is produced and an attempt is made to define the type of spreading centre represented. Comparison of the Masirah Ophiolite with the Semail Ophiolite of the Oman Mountains suggests that their former correlation may be ill founded. An assessment of late Mesozoic -early Tertiary plate motions indicates an origin during Cretaceous sea-floor spreading of an early Indian Ocean. Several features may indicate a slow-spreading, much-faulted, constructive margin.

Spatial and temporal trends of dissolved organic matter (DOM) were investigated in the Lower Kinabatangan River, Sabah, Malaysia over the period 2008-2012. The objectives were to: i. quantify DOM in areas of the catchment dominated by oil palm plantations; ii. characterise DOM quantity and quality in waters draining three contrasting land use types (oil palm plantations, secondary forests and coastal swamps); iii. characterise and interpret DOM quantity and quality in the main stem of the Kinabatangan river according to depth; and iv. infer differences in water movement through the catchment. Optical parameters, including fluorescence excitation-emission matrices (EEMs) and ultraviolet absorbance spectroscopy (UV-vis); and Parallel Factor Analysis were used throughout the investigation. The research comprised a preliminary catchment-wide study (225 samples) and concentrated fieldwork campaigns (510 samples). The results indicated the dominance of peaks C and M in waters from the oil palm plantations and coastal swamps respectively. The relative loss of terrestrial derived peaks could indicate progressive DOM degradation from the upper reaches towards the estuary. Results also showed DOM was transported back to the main river, as dominated by fluorescence index peak A/peak C, particularly in the coastal swamps. DOM characterisation with depth in the river, showed the dominance of peaks C and M (relative to terrestrial and microbial and/or photo-degradation processes) in waters near the riverbed.

A field study of cohesive sediment movements on a muddy intertidal zone (ITZ) at Portishead, Severn Estuary is presented. Five deployments of 1-3 days have been made to improve the understanding of temporal and spatial variations in suspended and bed sediments at a site which is found to be wave dominated. Pressure transducers, electro-magnetic current meters, optical turbidity meters and ultra-sonic bed level transducers are used to monitor the hydro/sediment dynamics in the bottom metre of the water column at two points on the ITZ. A one-dimensional (vertical) k-ϵ turbulence model has been modified to include bed sediment exchange and density stratification to enable further interpretation of field data. Modelling results show that the weak current on the ITZ would simply provide a mechanism for diffusing suspended sediment into the upper part of the flow, and does not enhance the wave boundary layer by its presence and cannot actively support suspended sediment. Hence near bed (wave generated) turbulence controls the vertical SSC distribution. A bed model based on bed sediment exchange via critical erosional and depositional shear stresses only predicts high near bed concentrations for some of the hydrodynamic conditions reflected in field data, suggesting hindered settling is an important factor in their formation. The introduction of density stratification reduces near surface SSC creating steeper SSC gradients in the upper half of the flow, for a weak current with waves.