An understanding of the longstream distribution of hydraulic processes is important for evaluating the mechanisms which control the catchment-scale variation of channel stability, sediment transport and siltation, flood generation and aquatic habitats. However, little attention has been given to quantifying the detailed spatial and temporal variability of channel hydraulic parameters, despite considerable attention to reach-scale processes. This study uses a combined field and modelling approach to define the distributions of channel hydraulic parameters between the source and the near-tidal limit of the River Severn, UK. Field measurements were made at 25 logarithmically-spaced sites along the Severn, under 3 flow conditions (low, medium and high) defined by exceedence frequencies. A flow event, occurring between 15-24 February 1989, was simulated by the 1-D hydraulic model, MIKE11. The simulated reach consists of cross sections spaced at 1 km intervals between 4 km and 254 km downstream from the source. Channel hydraulic parameters showed considerable variability in both space and time, reflecting cross section geometry variation downstream. Mean velocity increased with distance downstream from 0.23 m s\(^{-1}\) to 1.72 m s\(^{-1}\) under steady, bankfull flow conditions. However, unsteady flows simulated by MIKE11 demonstrated a longitudinal decline in the mean velocity of the wave peak associated with the rapid movement and minimal attenuation of the flood wave through the unconfined upper Severn. Flow resistance (Manning's n and Darcy-Weisbach f) decreased downstream from the source (0.32 - 0.06), although under low flow conditions it increased from 0.3 to 1.1 downstream to the non-alluvial - alluvial transition at Llanidloes; thereafter it exhibited a steady downstream decline. Reach mean shear stress and unit stream power peaked near the source (5-10 km downstream; drainage area < 50 km\(^2\)) at 120 N m\(^{-2}\) and 290 W m-2 and further downstream at the Ironbridge Gorge (170 km) (38 N m\(^{-2}\); 40 W m\(^{-2}\)) in response to the lithological controls on channel slope and valley width.

This research investigates what type of actors and organisations are involved in achieving the goal of providing more sustainable high quality urban regeneration in England. The research draws on three key strands of literature including sustainable urban development, development processes and governance. The research gap is where these three strands come together. The thesis explores these issues through the use of case studies in Hafencity (Hamburg) and 22@ (Barcelona) alongside consideration of major projects in England. The main findings of the research show that the continental case studies place stronger emphasis on proactive public sector management of projects (‘positive planning’) than would normally be the case in England. The public sector is able to lead the projects for reasons including land ownership, the planning system, skills in the planning department, use of a local development agency and a more positive and collaborative approach between the public and private sectors involving the appropriate use of power, partnerships and networks. This approach permits greater emphasis to be placed on long term / sustainability issues and helps to balance public interest and private sector gain, both of which could be of interest in the context of achieving more sustainable urban regeneration in England.

Studies of landscape development via primary successional processes are an important area of research for understanding how landscapes evolve into stable, diverse ecosystems. This research sought to assess how geomorphic and hydraulic complexity alter as streams develop following glacial recession. Investigations revealed that younger streams were dominated by fast flowing geomorphic units such as rapids and riffles with little hydraulic or landscape diversity. As stream age increased, however, slower flowing habitat units such as glides and pools became more dominant, resulting in increased geomorphic, hydraulic and riverscape diversity. Determination of these changes in hydromorphic complexity which occur as streams develop, twinned with an assessment of the role of coarse woody debris in creating such complexity at the reach and microscale levels revealed the importance of coarse woody debris in driving these changes. Coarse woody debris was found to influence the development of biocomplexity and interaction between stream, terrestrial and floodplain environments. These changes in geomorphic and hydraulic complexity result in the creation and maintenance of instream habitat which biota such as juvenile Pacific salmonids may utilise.

Glacial sediments, particularly diamicts, can be ambiguous to interpret. Fabric analyses, such as anisotropy of magnetic susceptibility (AMS), have been shown to provide specific information on the formation and subsequent deformation of glacial sediments. In this thesis, detailed investigations utilising the AMS technique have been combined with traditional sedimentological and structural techniques, to help resolve a number of current problems in glacial geology. At the same time, limitations of such uses of AMS have been established. In the modern environment (Tunabreen, Svalbard), magnetic lineations develop parallel to glacier flow and reveal dynamic behaviour during past surges. In a Quaternary glaciotectonite (Bacton Green Till Member, Norfolk, UK), AMS fabric develop in response to glacial deformation and reveal strain vectors that can be related to ice flow from contrasting directions. Finally in Neoproterozoic diamictites (Wilsonbreen Formation, Svalbard), despite local tectonic overprinting and diagenetic change, AMS can be used to reveal a dominant ice-flow to direction to the north. In combination with other sedimentological techniques, this has allowed the identification of glaciotectonic features and an ice-marginal, terrestrial and subaqueous model is proposed. These results support the use of AMS as a fast, objective and accurate technique that can facilitate the interpretation of cryptic glacial sediments.

Predicting contaminant movement in aquifers is essential for the protection of groundwater resources. Contaminant movement is strongly influenced by hydraulic property heterogeneity. The aim of this project has been to determine if hydraulic property values are correlated with geological structures, even if the aquifer is a cemented sandstone: if they are, the correlations could be used in gaining insight into, and quantitatively estimating, solute transport. Example Permo-Triassic sandstone lithofacies associations across England were examined in order to determine common lithofacies geometries. Several thousand measurements of permeability and several hundred measurements of porosity were determined on a core from northern England and two outcrops from the Midlands in order to examine correlations with lithofacies. Two types of synthetic fluvial multiple channel systems with flow a long and across channels were then numerically simulated to determine the significance of the correlations found. Results indicate that the Permo-Triassic sandstones have a wide range of lithologies and permeabilities, varying between and within sequences and regions. Permeability is generally greater for aeolian sandstone than for fluvial sandstone. The borehole core stud y shows that lithofacies correlate with porosity, permeability, and permeability to porosity ratio, though some significant overlaps occur for permeabilities of the three coarser lithofacies. Mudclasts can reduce sandstone permeability of the two coarser lithofacies by up to 6 % and 8% respectively. Markov chain analysis indicates that the sequences of lithofacies are structured, and hence the permeability is also similarly structured. The two outcrop studies confirm that permeability structures vary more between than within beds. Solute transport modelling indicates that differing solute breakthrough patterns will occur with different types of hydraulic property distributions based on lithofacies geometry. Thus lithofacies correlations can be used to help predict solute movement, but transverse dispersion, not explicitly studied here, also appears particularly important. Generally, the heterogeneous porous medium can be reasonably represented by an equivalent homogeneous medium for prediction purposes, however determining appropriate properties for the equivalent homogeneous medium is challenging.

Chalk streams are of high ecological value and are dependent upon groundwater discharge to support flows. This study investigates chalk stream-aquifer interaction, focusing on a near-natural catchment; the River Lambourn of the West Berkshire Downs. The topographic catchment of the Lambourn is 234km², principally underlain by Upper Chalk. The river has a perennial length of c.16km, and a 7.5km seasonal section. Temporal dynamics of the recharge-storage-discharge sequence are investigated using linear regression techniques to identify the lag between recharge and discharge. The effective maximum duration of groundwater flow is 9.1 months, which is used with regional hydraulic gradients to calculate a bulk (interfluve) hydraulic conductivity of 114m/d (using Sy=1%), suggesting that interfluve permeability has been historically underestimated. Spatial flow accretion on the Lambourn is defined from 12 reaches (each 1-2km long), exhibiting mean accretion rates between -0.019 and 0.211 cumecs/km. The accretion rate profile approximates a sinusoidal pattern (λ=12km) suggesting a catchment scale litho-structural control. However, local topography and lithology also exert influence. High accretion rate reaches are associated with major dry valley intersections and elevated valley floor permeability, whilst the presence of Chalk Rock at shallow depths restricts local accretion.

This study investigates the current impact of acid deposition on the structure and function of benthic communities in streams of contrasting pH in mid-Wales, UK, and examines barriers to biological recovery across the sites. The results of field surveys across 30 streams revealed sustained effects of acid stress on macroinvertebrate assemblages. Acid streams supported fewer grazers and filter-feeders than circumneutral waters but other functional groups were less affected by low pH. Field experiments tested the effects of acidification on two key processes in stream ecosystems, benthic algal grazing and leaf decomposition. Grazer impacts on algal abundance were generally feeble and largely unaffected by acid stress. Leaf litter decomposition was impaired by acidification, due largely to reduced microbial breakdown. Prospects for biological recovery in chemically restored streams are discussed, and field experiments were undertaken to test two hypotheses (biotic resistance and resource limitation) proposed to explain the observed delays in faunal recolonisation. A resident-colonist competition experiment revealed no evidence in support of biotic resistance as mediated through interspecific competition, whereas growth experiments revealed that the quality or palatability of algal resources in chemically ‘restored’ streams limits growth and survival of colonist mayfly nymphs (Baetis).

Magma-poor rifted margins (MPRMs) are characterised by extreme crustal attenuation that increases ocean ward, serpentinised mantle, detachment fault systems and low volumes of syn-rift magmatism. An apparent “extension discrepancy” exists at MPRMs, whereby the amount of stretching accommodated by seismically observable faults is far less than that required to thin the entire crust to the extent observed on wide-angle seismic and gravity models. Unrecognised polyphase faulting can accommodate the required extension. High degrees of stretching require polyphase faulting (PPF), so that the extension discrepancy may simply be a failure to recognise multiple generations of faulting at MPRMs. The polyphase faulting hypothesis is tested through the consideration of the structural geometries likely to result, generation of synthetic seismic images from those geometries and comparison of synthetic images with reflection seismic data from the hyper-extended Porcupine Basin. From this comparison, I have identified at least two cross-cutting fault generations on the margins of the Porcupine Basin. The models demonstrate PPF can accommodate extremely high strain but is practically un-interpretable when β ≥ c.2.5, remaining hidden on hyper-extended crust. Crustal embrittlement is achievable over two fault generations (minimum) leading to hyper-extension and mantle serpentinisation, with the remaining extension likely accommodated by serpentinite detachment systems.

The linkages between the stream and its riparian zone have been well studied in many diverse systems on short (generally annual) timescales. No research has yet considered this in the context of longer (multi-decadal to centennial) timescales at which landscape and successional processes operate. Glacier Bay National Park and Preserve, in southeast Alaska, has a well-documented history of glacial retreat, which allows for the study of ecosystem development using a space-for-time chronosequence approach. This research was unique in analysing terrestrial invertebrates on floodplains of different ages in Glacier Bay, and was the first to utilise two complementary methods of dietary analysis to study the movement of resources between terrestrial and aquatic habitats at sites of different ages. A combination of gut contents dietary analysis and stable isotope analysis was used to determine the food sources of aquatic and terrestrial consumers. Physical habitat complexity, rather than substrate age alone, was an important factor in structuring reciprocal subsidies. This has clear implications for river managers seeking to restore streams to their natural state, particularly where juvenile salmonids are present, as well as underlining the importance of considering a stream in the wider context of its riparian zone.

pH is a fundamental parameter controlling physicochemical processes in environmental systems. Cloud droplet pH controls the dissolution of important micronutrients (iron, phosphorus) which in turn affects the biological carbon pump and ultimately global climate. Using bulk cloud/fog water pH measurements to represent the whole pH spectrum can potentially lead to large errors in climate models. Optochemical sensors (optodes and nanosensors) have been developed for numerous analytes and applications. Optodes for pH however, are typically limited to biomedical applications due to their small pH sensing range (2 – 4 pH units). In this work, pH sensing optodes were developed ultimately combined into a single pH sensing optode with an extended range of pH 1-11. The optode material properties were re-designed to allow for the collection, storage and analysis of individual droplets on the sensor surface. Core-shell pH nanosensors were also developed and used to map the pH distribution within the model organism Daphnia magna, the pH along the gut was found to range from pH 5.8 – 7.2. Finally, a device (electrostatic precipitator) for collecting individual cloud/fog droplets was designed and constructed. The electrostatic precipitator was used in conjunction with the optodes to deposit and measure pH in standard (artificial) cloud/fog droplets under laboratory conditions.