Longitudinal subglacial bedform semi-automated mapping and measurement

This thesis addresses methodological issues in the morphometric inventorying of relict drumlins and mega-scale glacial lineations (longitudinal subglacial bedforms, LSBs) which pose limits to a robust description of LSB morphometry and thus to testing hypotheses of LSB genesis, with implications for postdicting past, and predicting future, ice sheet behavior. Focus is on a) the adequacy of previously used morphometric measurement methods (MMM) (GIS) and b) the development of LSB semi-automated mapping (SAM) methods. Dimensions derived from an ellipse fitted to the LSB footprint based on Euler’s approximation are inaccurate and both these and orientation based on the longest straight line enclosed by the footprint are imprecise. A newly tested MMM based on the standard deviational ellipse performs best. A new SAM method outperforms previous methods. It is based on the analysis of normalized local relief closed contours and on a supervised ruleset encapsulating expert knowledge, published morphometric data and study area LSB morphometry

Measuring (Subglacial) Bedform Orientation, Length, and Longitudinal Asymmetry – Method Assessment

Geospatial analysis software provides a range of tools that can be used to measure landform morphometry. Often, a metric can be computed with different techniques that may give different results. This study is an assessment of 5 different methods for measuring longitudinal, or streamlined, subglacial bedform morphometry: orientation, length and longitudinal asymmetry, all of which require defining a longitudinal axis. The methods use the standard deviational ellipse (not previously applied in this context), the longest straight line fitting inside the bedform footprint (2 approaches), the minimum-size footprint-bounding rectangle, and Euler’s approximation. We assess how well these methods replicate morphometric data derived from a manually mapped (visually interpreted) longitudinal axis, which, though subjective, is the most typically used reference. A dataset of 100 subglacial bedforms covering the size and shape range of those in the Puget Lowland, Washington, USA is used. For bedforms with elongation > 5, deviations from the reference values are negligible for all methods but Euler’s approximation (length). For bedforms with elongation < 5, most methods had small mean absolute error (MAE) and median absolute deviation (MAD) for all morphometrics and thus can be confidently used to characterize the central tendencies of their distributions. However, some methods are better than others. The least precise methods are the ones based on the longest straight line and Euler’s approximation; using these for statistical dispersion analysis is discouraged. Because the standard deviational ellipse method is relatively shape invariant and closely replicates the reference values, it is the recommended method. Speculatively, this study may also apply to negative-relief, and fluvial and aeolian bedforms

Simulation of groundwater flow in mountain watersheds

Many mountain watersheds provide a reliable source of freshwater for habitat and human use downstream. Hydrodynamics of these basins can be particularly sensitive to change, which may arise from climate change, natural/anthropogenic alteration and other forcing. The timing and intensity of runoff and the recharge of groundwater must be at least partially understood to simulate the potential effects of change. The effects of groundwater on basin drainage are often neglected in simulations due to a lack of empirical data. This study focused on the integration of remote sensing data, geomorphic principles, theoretical distributions of heterogeneity, basin discretization methods, and saturated flow computation to apply a novel technique to understand groundwater behaviour in mountain watersheds. Methods included a geomorphometric analysis to computationally simulate the distribution of geomorphic landforms, which were used to estimate heterogeneity in the shallow subsurface and provide opportunity to evaluate groundwater flow. Morphometric attributes of various landforms were studied and compared to their genetic origin to identify potential landforms. The resulting landforms were subsequently divided into equivalent porous media units (EMUs) based on the theoretical distribution of heterogeneity within landform types. EMUs were evaluated as irregular units used to discretize a saturated groundwater flow model. Groundwater flow was calculated using recharge simulated by any hydrometeorologic model and was routed using Darcian flow from EMU to EMU. Methods of simulating groundwater flow in this study were found to be well suited for the basin type of the study area used (St. Mary Watershed, Montana, USA), albeit with limitations. Results of the geomorphometric analysis compared well with published surficial geology data. The basin discretization method presented in this research would benefit from implicit groundwater flow solving, and application in a basin where abundant data exist. An implicit scheme would allow faster computation and provide the means for a quantitative comparison of basin outflow and water table elevations, which would be useful to further evaluate the suitability of these techniques

Semi-automated geomorphological mapping applied to landslide hazard analysis

Computer-assisted three-dimensional (3D) mapping using stereo and multi-image (“softcopy”) photogrammetry is shown to enhance the visual interpretation of geomorphology in steep terrain with the direct benefit of greater locational accuracy than traditional manual mapping. This would benefit multi-parameter correlations between terrain attributes and landslide distribution in both direct and indirect forms of landslide hazard assessment. Case studies involve synthetic models of a landslide, and field studies of a rock slope and steep undeveloped hillsides with both recently formed and partly degraded, old landslide scars. Diagnostic 3D morphology was generated semi-automatically both using a terrain-following cursor under stereo-viewing and from high resolution digital elevation models created using area-based image correlation, further processed with curvature algorithms. Laboratory-based studies quantify limitations of area-based image correlation for measurement of 3D points on planar surfaces with varying camera orientations. The accuracy of point measurement is shown to be non-linear with limiting conditions created by both narrow and wide camera angles and moderate obliquity of the target plane. Analysis of the results with the planar surface highlighted problems with the controlling parameters of the area-based image correlation process when used for generating DEMs from images obtained with a low-cost digital camera. Although the specific cause of the phase-wrapped image artefacts identified was not found, the procedure would form a suitable method for testing image correlation software, as these artefacts may not be obvious in DEMs of non-planar surfaces.Modelling of synthetic landslides shows that Fast Fourier Transforms are an efficient method for removing noise, as produced by errors in measurement of individual DEM points, enabling diagnostic morphological terrain elements to be extracted. Component landforms within landslides are complex entities and conversion of the automatically-defined morphology into geomorphology was only achieved with manual interpretation; however, this interpretation was facilitated by softcopy-driven stereo viewing of the morphological entities across the hillsides.In the final case study of a large landslide within a man-made slope, landslide displacements were measured using a photogrammetric model consisting of 79 images captured with a helicopter-borne, hand-held, small format digital camera. Displacement vectors and a thematic geomorphological map were superimposed over an animated, 3D photo-textured model to aid non-stereo visualisation and communication of results

Geomorphic responses to natural and human disturbances in a mountain catchment at multiple temporal and spatial scales

Aquesta tesis es centra en l’estudi de la transferència d’aigua i sediments des de les àrees font de sediments fins les zones de sedimentació a múltiples escales temporals (des de dades amb una freqüència de cinc minuts fins informació de tot un segle) i espacials (des de vessants fins a conques), i les seves implicacions en la morfologia de la llera de la conca de l’Alt Cinca, una conca de muntanya localitzada al vessant sud dels Pirineus. A escala de micro-conca, les dades d’alta resolució obtingudes durant 5 anys en dos badlands contrastats (0.3 ha cadascun) revelen com la pluja controla els processos erosius associats a l’escolament superficial, m’entre que les baixes temperatures tenen una relació significativa amb els processos de moviments en massa. La morfometria d’aquestes superfícies, conjuntament amb la cobertura vegetal són factors clau que determinen els principals processos geomorfològics i els associats canvis topogràfics. Els principals processos observats han estat seqüències d’Erosió i Sedimentació (Cutting and Filling) i Moviments Gravitacionals (Mass Wasting). Tot i que els badlands tenen un paper important en la producció de sediments, el balanç de sediments de la conca del riu Soto (10 km2) indica que aquestes superfícies no sempre controlen l’exportació de sediments a la sortida de petites conques de muntanya amb caràcter intermitent. Aquest fet és degut a la fluctuació de la connectivitat funcional de la xarxa de drenatge causada per la freqüència i magnitud dels polsos d’aigua i sediments durant crescudes sobtades o flashy. La xarxa de drenatge actua com a font i zona d’emmagatzematge de sediments i es clau per entendre les marcades diferències que hi ha en la proporció del sediment que s’exporta en relació a la producció o també anomenat Sediment Delivery Ratio. Els canvis en els usos de sòl en moltes conques de muntanya constatats des de els anys 50 del segle XX tenen un efecte directe en la generació d’escolament (quantitat i magnitud) i en la producció de sediments. La majoria de la superfície de la conca de l’Alt Cinca (1565 km2) ha sofert aforestació, que ha resultat en una reducció de la connectivitat sedimentaria estructural. La construcció de terrasses afecta la connectivitat molt més que els canvis en la coberta del sòl. Les terrasses generalment redueixen la connectivitat degut a l’establiment de zones planes entre mig de zones en pendent. Contràriament, a una escala més local, les terrasses poden incrementar la connectivitat degut a la convergència de flux produïda per les pròpies estructures, o per la caiguda d’aquestes degut a l’abandonament. La construcció de carreteres modifica el pendent i la xarxa de drenatge, fet que comportarà canvis en la connectivitat estructural, que a la vegada poden afectar els processos erosius en les zones veïnes. Així, els fluxos d’aigua i sediments a la conca de l’Alt Cinca han estat àmpliament modificats durant l’últim segle, amb implicacions directes en la forma de la llera. A més a més, impactes locals derivats de les extraccions d’àrids, construcció d’esculleres i embasaments també han condicionat la dinàmica sedimentaria d’aquest riu, amb un impacte directe sobre la morfologia. Aquesta situació ha generat una metamorfosis de la morfologia del riu en la part baixa de l’Alt Cinca (12 km), canviant d’un patró trenat, molt dinàmic, a un patró més estable amb una tendència cap a canal únic. Els resultats obtinguts indiquen que el tram d’estudi està assolint un nou equilibri morfo-sedimentari imposat pels canvis en els fluxos d’aigua i sediments ocorreguts en el darrer segle, incloent les pertorbacions antròpiques que han modificat la geometria del canal i les característiques morfològiques de la llera. S’han observat un total de tres fases en la seva evolució: abans de l’any 1927, el tram d’estudi es trobava en una situació de quasi-equilibri majoritàriament condicionada per les riuades. Entre l’any 1927 i 2012 el riu s’ha ajustat a les diferents pertorbacions que ha tingut a múltiples escales temporals i espacials. Aquest ajust s’ha portat a terme mitjançant dos canvis contrastats en les característiques morfològiques. Finalment, després de l’any 2012, els resultats indiquen que el riu pot haver assolit de nou un nou equilibri, ajustant-se als fluxos d’aigua i sediment imposats i a la nova configuració del canal. Aquesta tesis presenta innovadors mètodes quantitatius per a l’estudi de la producció de sediments i la transferència entre els diferents compartiments de les conques fluvials. La principal novetat en la majoria dels capítols de la tesis recau en l’elevada resolució, de les dades obtingudes, tant temporal com espacial. Els resultats obtinguts en aquesta tesi permeten entendre millor el funcionament dels sistemes fluvials i la seva evolució, aspectes claus per donar suport en la millora i gestió de conques hidrogràfiques de muntanya.Esta tesis se centra en el estudio de la transferencia de agua y sedimentos desde las áreas fuente de sedimentos hasta las áreas de sedimentación a múltiples escales temporales (desde datos con una frecuencia de cinco minutos hasta información de un siglo) y espaciales (desde laderas hasta cuencas), y sus implicaciones en la morfología del cauce en la Cuenca del Alto Cinca (vertiente sur de los Pirineos). A escala de micro-cuenca, los datos de alta resolución obtenidos durante 5 años en dos badlands contrastados (0.3 ha cada uno) revelan como la lluvia controla los procesos erosivos asociados a la escorrentía superficial, mientras que las bajas temperaturas tienen una relación significativa con los procesos de movimientos en masa. La morfometría de estas superficies, conjuntamente con la cobertura vegetal, son factores clave que determinan los principales procesos geomorfológicos y los cambios topográficos asociados. Los principales procesos observados han sido secuencias de Erosión y Sedimentación (Cutting and Filling) y Movimientos Gravitacionales (Mass Wasting). Pese a que los badlands tienen un papel importante en la producción de sedimentos, el balance de sedimentos de la cuenca del rio Soto (10 km2) indica que estas superficies no siempre controlan la exportación de sedimentos a la salida de pequeñas cuencas de montaña con carácter intermitente. Esto principalmente se debe a la fluctuación de la conectividad funcional de la red de drenaje causada por la frecuencia y magnitud de los pulsos de agua y sedimentos durante las crecidas súbitas o flashy. La red de drenaje actúa como fuente y zona de almacenamiento de sedimentos, y es clave para entender las marcadas diferencias que hay en la proporción de sedimento que se exporta en relación a la producción o Sediment Delivery Ratio. Los cambios en los usos del suelo en muchas cuencas de montaña constatados desde los años 50 del siglo XX tienen un efecto directo en la generación de escorrentía (cantidad y magnitud) y en la producción de sedimentos. La mayoría de la superficie de la cuenca del Alto Cinca (1565 km2) ha sufrido forestación, que ha resultado en una reducción de la conectividad sedimentaria estructural. La construcción de terrazas afecta la conectividad mucho más que los cambios en la cobertura del suelo. A una escala más local, las terrazas pueden incrementar la conectividad debido a la convergencia de flujo producida por las propias estructuras, o por la caída de estas debido a su abandono. La construcción de carreteras modifica la pendiente y la red de drenaje, hecho que comporta cambios en la conectividad estructural, que a su vez pueden afectar a los procesos erosivos en las zonas vecinas. Así, los flujos de agua y sedimento en la cuenca del Alto Cinca han estado ampliamente modificados durante el último siglo, con implicaciones directas en la morfología del canal. Además, impactos locales derivados de las extracciones de áridos, construcción de escolleras y embalses también han condicionado la dinámica sedimentaria de este río, con un impacto directo sobre la morfología. Esta situación ha generado una metamorfosis de la morfología del río en la parte baja del Alto Cinca (12 km), cambiando de un patrón trenzado, muy dinámico, a un patrón más estable con una tendencia hacia el canal único. Los resultados obtenidos indican que el tramo de estudio está alcanzando un nuevo equilibrio morfo-sedimentario impuesto por los cambios en los flujos de agua y sedimentos ocurridos durante el último siglo, incluyendo las perturbaciones antrópicas que han modificado la geometría del canal y las características morfológicas del cauce. Se han observado un total de tres fases en su evolución: antes de 1927, el tramo de estudio se encontraba en una situación de casi-equilibrio, mayoritariamente controlada por las crecidas. Entre el año 1927 y 2012 el río se ha ajustado a las diferentes perturbaciones que ha tenido a múltiples escalas temporales y espaciales. Este ajuste se ha llevado a cabo mediante dos cambios contrastados en las características morfológicas. Finalmente, después del año 2012, los resultados indican que el río puede haber alcanzado un nuevo equilibrio, ajustándose a los flujos de agua y sedimento impuestos y la nueva configuración del canal. Esta tesis presenta innovadores métodos cuantitativos para el estudio de la producción de sedimentos y la transferencia entre los diferentes compartimentos de las cuencas fluviales. La principal novedad en la mayoría de los capítulos de la tesis recae en la elevada resolución de los datos obtenidos, tanto temporal como espacial. Los resultados obtenidos en esta tesis permiten entender mejor el funcionamiento de los sistemas fluviales y su evolución, aspectos clave para dar soporte y apoyo en la mejoría y gestión de cuencas hidrográficas de montaña.This thesis focusses on the study of water and sediment transfer from sources to sinks at multiple temporal (from 5-min data to a century data sets) and spatial (from slope to catchment scales) scales and their implications for channel morphology in the Upper Cinca catchment, a mountain catchment located in the Southern Pyrenees. At the micro-catchment scale, our 5-year High Resolution Data Set of two contrasted badlands (around 0.3 ha each) reveal as rainfall control overland-surface flow processes while low temperatures have a significant relation with mass movement-based processes. Morphometry together with vegetation cover are key factors determining main geomorphic processes and associated topographic changes. Main observed geomorphic processes were Cutting and Filling and Mass Wasting. Although badlands may have an important role on sediment production, the 2-year sediment budget of the Soto catchment (10 km2) indicates that badlands do not always control the export of sediments at the outlet of small intermittent mountain catchments. This is mainly due to the fluctuation of the functional connectivity of the channel network caused by the frequency and magnitude of water and sediment pulses during flashy floods. The channel drainage network acts as sediment source and sink and it is key to understand marked differences in the Sediment Delivery Ration. Land use and cover in many mountain catchments have been modified since the fifties of the 20th century, having a direct effect on runoff and sediment production. Most of the area of the Upper Cinca catchment (1565 km2) has undergone afforestation, which resulted in a decrease of structural sediment connectivity. Terracing affects connectivity much more than changes in land cover. Terraces generally reduce connectivity due to the establishment of flat areas between slopes and, contrarily, locally, may increase connectivity due the convergence produced by the structures or the collapse of terraces due to abandonment. Road construction, however, modify slope and the drainage network, which leads to changes in connectivity that could affect erosional processes in the neighbouring areas. Thus, water and sediment fluxes through the Upper Cinca are spatially and temporal dynamic and have been dramatically modified in the last century, with direct implications on channel morphology. Additionally, localised disturbances such as gravel mining, channel embankments and dams have also impacted on sedimentary dynamics, thus channel morphology. This situation led to a river metamorphosis, changing from a braided pattern to a more static channel towards a wandering pattern. We hypothesise that the lowermost 12-km reach of the Upper Cinca has reaching a new equilibrium imposed by catchment-scale changes of water and sediment fluxes caused by global changes, but also influenced by localised human-disturbances that modify channel geometry and morpho-sedimentary characteristics. Three phases were identified: before 1927, the reach remained in a quasi-equilibrium state imposed, mainly, by water and sediment supply during flood events. During the period 1927-2012 the river adjusted to the disequilibrium imposed by disturbances acting at different temporal and spatial scales, yielding two contrasted channel states. Finally, after 2012, we hypothesise that the river may be reaching again a new equilibrium, adjusting to the imposed water and sediment fluxes and the new channel configuration. This thesis presents some novel quantitative methods for the study of sediment production and transfer between the different compartments of fluvial catchments. The main transversal novelty in all the methods used in each chapter lies in the high resolution of the data obtained. This comprehensive analysis aids at understanding the functioning of the river system and their evolution based on multiple-scale disturbances, which can help to support integrated watershed management practices or plans

The drumlin problem : streamlined subglacial bedforms in southern Sweden

This thesis investigates stream-lined subglacial bedforms (often referred to as drumlins) in southern Sweden. The broad aim of this is to contribute to the solution of the ‘drumlin problem’. The term drumlin has come to be applied to a wide range of features whose internal architecture (core) and overall morphology are seen to vary greatly. This range in characteristics is in part responsible for the various competing theories of drumlin formation, each different type of core and morphology generating a new idea for how it came about. Here the new Swedish national height model, a high resolution LiDAR derived digital elevation model, in combination with detailed sedimentological work is used to characterise streamlined terrain in southern Sweden and investigate the formation processes associated with it. The findings of this are that drumlinoids in southern Sweden are predominantly rock cored. Soft cored features tend to be significantly longer than rock cored features. In general, drumlinoids in southern Sweden are located at the lower end of the size spectrum in terms of global streamlined sub-glacial features. Additionally it has been found that drumlinoids can form rapidly at glacial margins as well as within the main body of ice sheets. And finally, the most important contextual geological factor in drumlinoid parameter (morphology) formation appears to be drift depth/properties. The bedrock type beneath a feature and the hydrological system as recorded in eskers do play a role, but the exact nature of this is not certain and the correlations are difficult to analyse. In addition to these findings a generalised conceptual model of drumlinoid formation is proposed and a discussion of the possible ways in which physical processes influence said formation is offered. It is suggested that chaotic behaviour and the role of scale might be useful to consider and that whilst it is something of semantic point, the use of the term drumlinoid is deliberate and important. This is because due to equifinality there are many landforms that researchers can split into different categories, e.g. rock drumlins, clone drumlins, emergent drumlins, downwards emergent drumlins or obstacle drumlins. These are all valid divisions as there are different physical processes involved in their formation. However these processes and the final landforms that result from them are all part of the sub-glacial continuum and so at one level must be considered part of the same family

THE DEVELOPMENT OF A HOLISTIC EXPERT SYSTEM FOR INTEGRATED COASTAL ZONE MANAGEMENT

Coastal data and information comprise a massive and complex resource, which is vital to the practice of Integrated Coastal Zone Management (ICZM), an increasingly important application. ICZM is just as complex, but uses the holistic paradigm to deal with the sophistication. The application domain and its resource require a tool of matching characteristics, which is facilitated by the current wide availability of high performance computing. An object-oriented expert system, COAMES, has been constructed to prove this concept. The application of expert systems to ICZM in particular has been flagged as a viable challenge and yet very few have taken it up. COAMES uses the Dempster- Shafer theory of evidence to reason with uncertainty and importantly introduces the power of ignorance and integration to model the holistic approach. In addition, object orientation enables a modular approach, embodied in the inference engine - knowledge base separation. Two case studies have been developed to test COAMES. In both case studies, knowledge has been successfully used to drive data and actions using metadata. Thus a holism of data, information and knowledge has been achieved. Also, a technological holism has been proved through the effective classification of landforms on the rapidly eroding Holderness coast. A holism across disciplines and CZM institutions has been effected by intelligent metadata management of a Fal Estuary dataset. Finally, the differing spatial and temporal scales that the two case studies operate at implicitly demonstrate a holism of scale, though explicit means of managing scale were suggested. In all cases the same knowledge structure was used to effectively manage and disseminate coastal data, information and knowledge

Visualization of Uncertain Boundaries of Undersea Features

There have been several studies that detect, measure, analyze, and visualize the undersea features by using technologies in multiple disciplines including geography and oceanography. However, definitions of the undersea features often vary among the existing leading literature. Due to this reason the geographical boundary for a certain undersea feature is sometimes not identical among the definitions. In this study, we explore semantic uncertainty in the definitions of some undersea features and apply approaches from fuzzy-set theory and geographic information science on empirical bathymetric data to visualize the uncertain boundaries of the undersea features. Results from this study demonstrate that the representation based on the fuzzy-set approach can be useful for dealing with the semantic uncertainty of the undersea features