Hydrological, hydrochemical and sedimentological observations were undertaken in the catchments of Feevispa (Feegletscher), Findelenbach(Findelengletscher) and Gornera (Gornergletscher), Swiss Alps, in an attempt to use meltwater characteristics as indicators of the nature and functioning of glacial hydrological systems. Annual and seasonal hydrographs of the Feevispa allowed calculation of catchment water balance. Considerable annual variation resulted from excess icemelt over snow accumulation giving greater outputs than inputs. Diurnal hydrograph analysis showed that large quantities of water are stored in Feegletscher and Gornergletscher. Rapid erratic fluctuations of subglacial sediment supply caused involutions in daily clockwise suspended sediment concentration-discharge hysteresis loops in the Gornera. During draining of the Gornera, exceptionally high discharges evacuated large quantities of sediment from beneath Gornergletscher, but bequeathed no lasting impact on conduit capacity. Close interval sampling and continuous monitoring of sediment concentration permit interpretation of the nature of ice-meltwater-sediment interactions on Alpine glacier beds. Chemical composition of meltwaters emerging from the glacier portals was monitored during several ablation seasons. Electrical conductivity, a surrogate measure of ionic content, was continuously recorded and Na+, K+, Ca2+ and Mg2+ determined by atomic absorption spectrophotometry. Meltwaters from glacier surfaces have low solute contents, of atmospheric origins, whereas after passage through internal conduits; meltwaters become chemically enriched from lithospheric contact. Marked diurnal variations (clockwise hysteresis) of solute concentration in portal meltstreams reflect the mixing in varying proportions through time of waters of different compositions, delimiting trapezoidal solute concentration discharge relationships. Two components of discharge through Findelengletscher and Gornergletscher were separated on the basis of chemical composition using a simple mass-balance mixing model. A large proportion of total flow passes rapidly through major moulin-arterial canal networks. For basal flow, two contrasting regimes were discriminated, both independent of (Findelengletscher) and interlinked with (Gornergletscher) cavity storage at the ice-bedrock interface.

Rates of river channel change in three contrasting Scottish upland environments have been studied within the context of Climatic fluctuation and landuse changes over the last 250 years. The object of the research was to assess the spatial and temporal variation in channel types, the main controls on channel pattern and the dominant modes of channel adjustment. This was undertaken in a hierarchic framework with sites being investigated at three spatial scales. At a macro-scale, the spatial and temporal variation in channel pattern was evaluated through a random sample of river channel segments for each study area, derived from the first and second editions of the 1:10,560 0.S. maps plus the 1:10,000 third edition. Each channel segment was classified within a map-based channel system typology, specifically constructed for upland Scotland. Measures of activity collected for each sample incorporated sinuosity, braiding and lateral shift indices. Flood histories were reconstructed for each study area on the basis of discharge records, long rainfall records and contemporary accounts, to assess if there was any evidence for climatic change, fluctuation or periodicities. Estimates of the recurrence interval of rainfall and runoff events of differing magnitude, frequency and duration were assessed. Data, mainly of a qualitative nature, were derived from contemporary sources and estate plans to evaluate whether any landuse changes could have changed the runoff regime and sediment mobility within each catchment. At a meso-scale, 7 to 9 channel segments (already identified as "active" within the macro-scale study) were subject to a more detailed process-response analysis, using sequential aerial photographs. Finally at a micro-scale, the unit stream powers at these sites were studied in relation to specific runoff rates thereby relating channel process to channel form. The strength of the controls on channel planform type varied in degree with the area studied. The glacial legacy, the positioning of local baselevels and sediment size were found to be dominant controls. In terms of channel dynamics, the position of the Channel planform in relation to process thresholds and the existence of a quasi-equilibrium condition were both very important. In terms of process-response, the following general observations hold true. An extreme event of high RI (>100 years) will have a major disruptive impact if there is room for expansion of the channel system and providing thresholds for sediment transport are exceeded. If these thresholds are high, the fact that the channel has not recently been disrupted may also be important. The modes of expansion across the active area depend on the type of channel involved. Different study areas have different types of Channel pattern present and thus a greater likelihood of certain types of planform adjustment. The role of more moderate events (10-50 years) varies principally with sediment size and Channel slope. Small-scale modification may take place where stream powers associated with more moderate events exceed competence thresholds. It was found that process rates were highly variable in both time and space and that present rates were not necessarily representative of the past 250 years. Even within this timespan, there have been periods of increased activity in response to increased discharges of moderate magnitude (eg. 1870s-1880s within the Dee study area) and random extreme magnitude floods (eg. between 1948-1956 in the Tweed study area). The impact of landuse change, especially in relation to sediment mobilisation (Dee and Spey study areas), and speed of runoff (Tweed study area) also appeared to be important.

No description available.

No description available.

This thesis describes an investigation of the flood response of Burnes Gill and Force Beck, two upland catchments in the North West Pennines. The objectives of the study were to examine whetler an understanding of the catchment processes which generate flood runoff can be used to improve the structure of existing flood estimation techniques or their. application at the ungauged site. Rainfall, discharge and soil moisture were measured over a period of two years on two small catchments with contrasting topography and geology. Flood response was defined by the magnitude and volume of separated discharge and related to rainfall depth, intensity and several direct and indirect estimates of catchment wetness. The average response was lower and less dependent on antecedent wetness on Burnes Gill, one of the steepest gauged catchments in the United Kingdom than on the flatter Force Beck catchment. This difference in response was related to the contributing areas of the two catchments, defined by neutron probe measurements and field survey. The implications of these results for flood estimation at the ungauged site in the United Kingdom are illustrated by considering the Transport and Road Research Laboratory and Flood Studies Report flood design techniques.

Perimarine river valleys are a rich resource for studying palaeoecological change which may provide information concerning catchment and sea-level change. This thesis reconstructs the environmental history of the lower Aire valley during the Holocene, and investigates the factors influencing floodplain and vegetational development.Reconstruction of environmental change in the lower Aire valley in the mid- to late-Holocene is based on lithological and palaeoecological records from three sites in the upper, middle, and lower parts of the study reach. Techniques used include pollen, diatom, wood macrofossil, loss on ignition, and radiocarbon analysis.Paludification of the valley floor was time transgressive, apparently responding to gradually rising sea level, beginning at c. 7000 BP (c. 8000 to c. 7600 cal. yrs BP) at the lowermost site, whereas conditions were not wet enough for preservation of organic sediment in the upper reach until c. 4200 BP (c. 5000 to c. 8500 cal. yrs BP). Accumulation of floodplain peat was interrupted by the deposition of finely laminated humic clays some time after c. 7000 BP (c. 8000 to c. 7600 cal. yrs BP) in the lower tract of the Aire valley, near Goole, suggesting a change to lagoonal conditions. This was apparently caused by the ponding of freshwater against the rising estuary. It is also possible that drainage was impeded, associated with widespread deposition of organic sediment in the lower valley areas, which may have contributed to the creation of a lagoonal environment. The lagoon had silted up by c. 6000 BP (c. 7200 to c. 6600 cal. yrs BP), probably due to an increase in tidal asymmetry, and range, which resulted in a net surplus of sediment into the floodbasins and enabled the re-invasion of fen carr onto the site.The main period of organic sedimentation lasted for several millennia at each of the study sites, during which time Alnus glutinosa fen carr communities dominated the wet floodplain backswamp areas. During mid-Holocene times, the vegetation of the surrounding dryland, was colonised by a mixed woodland, with Tilia, Ulmus, Quercus, and probably, Corylus avellana and Fraxinus excelsior. Pinus sylvestris was also prevalent in the region.Alnus carr was progressively replaced by fen meadow communities, and then saltmarsh or freshwater reedswamp communities, due to a phase of positive sea-level tendency, which was recorded throughout the lower Aire valley between c. 4600 and c. 2700 BP (c. 5500 to c. 2700 cal. yrs BP). Remnants of a possible upper peat unit and diatom evidence from the upper clastic sediment is tentatively interpreted as indicating the contraction of estuarine conditions and a phase of negative sea-level tendency some time during the late-Iron Age.

No description available.

No description available.

Surface interpolation and, more particularly isarlthm interpolation are common procedures in the Earth Sciences and increasingly common ones in most other disciplines. Data for such Interpolation are increasingly being stored in a computer-accessible form as a prerequisite to a computer-derived solution. This has resulted in the development of a large assortment of computer software to perform the interpolation. The scientist is thus faced with a predicament of which is the optimum method of isarlthm interpolation for his data- This thesis describes an empirical evaluation of the performances of a comprehensive selection of software in relation to data characteristics. Much of the software is available in the academic environment or was developed by the author. The evaluation utilises detailed, photogrammetrically derived digital terrain data which are related to some currently used data classification systems. Additionally, several techniques, mostly derived from geomorphometry, are used to examine the data in more depth, in an attempt to establish reliable descriptors of their data characteristics. These descriptors are designed to be used in a multi-disciplinary environment. The interpolation process is essentially classified into three stages for evaluation. Random-to-grid algorithms are evaluated by considering the interpolated grid in relation to an observed grid. Grid-to-isarithm and random-to-isarithm interpolation are evaluated by considering the interpolated Isarithms with observed isarithms. In both cases, geometric errors and the morphological trueness of the interpolation product are considered using graphical and numerical parameters. These statements of accuracy are correlated with the data characteristics to establish the main factors influencing isarithm interpolation.

No description available.