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The shallow aquifer of the Badain Jaran Desert represents the sole water supply to a distinctive oasis lake ecosystem and related small-scale agriculture. Despite environmental concern and high demand for water resources to support development in II II (7') ~) i Ii f northwestern China, few investigations have provided information on sources or rates of groundwater recharge. This study was undertaken in order to derive a sound conceptual model of recharge to this desert aquifer using multiple environmental tracer approaches. It represents one of the first detailed investigations of recharge in cold arid environments. Unsaturated zone chloride mass balance indicates that direct recharge through unconsolidated sands occurs at a rate of approximately 1 mm1yr. This represents 1.5% of annual rainfall, a similar ratio to many warm deserts worldwide. While spatial variability in diffuse recharge is found to be remarkably low, temporal variability in deep drainage over the last 700 years is observed from pore moisture chemistry and is attributable to fluctuations in the influence of the East Asian Summer Monsoon. Stable isotope compositions confirm that direct recharge is not a major recharge source to the desert's southeastern section.

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The mechanisms that control glacier dynamics and fast ice stream flow are still poorly understood, largely due to the inaccessibility of the subglacial environment. One of the ways to improve on current investigations is to broaden the methods used to monitor the subglacial environment. An autonomous multi-sensor wireless probe was developed for use within an Environmental Sensor Network at Briksdalsbreen, Norway. Probes were deployed at the base of boreholes, measuring temperature, pressure, resistance (a proxy for conductivity), case strain, and tilt, six times a day. The probes used radio_communications to....transfer data to a base station at the glacier surface. The data was then sent to a reference station, which uploaded it onto the internet on a daily basis. In excess of a year's worth of data was obtained from several probes, deployed between 2004-2006. Readings of case strain and tilt indicated when the probes had become incorporated into the deforming bed. A reduction in sensor activity was displayed as the glacier changed from a summer to a winter regime. In the following spring, the sensors showed an increase in activity, particularly in water pressure. An Emergent Spring Event was recorded in February, followed by the actual Spring Event. This marked a transition to summer conditions within the glacier's hydrological system. Sliding was the dominant mechanism ofbasal motion during this time. In the summer, the probes began to rotate as the dominant form of basal motion transferred from sliding to till deformation. The movement of the probes was in keeping with the Taylor (1923) mechanism of clast rotation. Sedimentological analyses under the scanning electron microscope presented a relatively simple model for grain erosion within the deforming bed. Erosion occurs within a continuum whereby processes of both fracture and abrasion combine, generating intermediate grain forms. The style of deformation experienced is controlled by the nature of the bedrock and the overall strain imposed on the till. At Briksdalsbreen there was good evidence for erosion, but little evidence for the production of a significant silt component. This investigation demonstrates the potential for the use ofESNs within glacial environments. The probes provide a successful means by which the properties of and processes operating within the subglacial environment can be assessed over broad temporal and spatial scales. For the first time, activity was recorded within the subglacial environment much earlier than previously expected (January) and the spring event within unconnected regions of the bed was monitored and characterised. The records produced highlighted the complexity of hydro-mechanical interactions and the need for further study to constrain these processes. The probes also provided the first natural records of in situ clast rotation from within the deforming bed. This movement may have implications for models of clast rotation, the identification and classification of sediments, and models of grain interactions on the micro-scale.

Repeat topographic surveys are often used to monitor geomorphological change in rivers. Such surveys can yield Digital elevation models (OEMs), which are differenced against each other to produce spatially distributed maps of elevation changes called OEMs of difference (000). Both areal and volumetric budgets of erosion and deposition can be calculated from DoOs. However, questions arise about the reliability of the analyses and what they mean. This thesis presents two new methodological advances to address these two uncertainties. The question of reliabilities (reliability uncertainty) was addressed through the development of a flexible technique for estimating the spatially variable surface representation uncertainties in individual OEMs. A fuzzy inference system is used to quantify uncertainty in OEMs and .' the individual error estimates are propagated into the 000 on a cell-by-cell basis. This is converted into a probabilistic estimate of 000 uncertainty. This estimate can be improved using Bayes theorem and an analysis of the spatial coherence of erosion and deposition units within the 000. The resulting probabilistic estimate of 000 uncertainty reflects the spatial variability of uncertainty, and can be used to threshold the 000 at user-specified confidence intervals. This addresses reliability by allowing the distinction between real and undetectable changes. The question of what the thresholded DoDs mean, geomorphically, is a fundamental one and what originally motivated the development of morphological sediment budgeting techniques. Herein, a range of masking tools were developed, which allow the quantitative interrogation of these rich spatial datasets and their patterns based on various classification systems and/or the expert-judgment of a trained geomorphologist. The tools extend the traditional 000 interpretation of whether a reach is jet aggradational or net degradational to a detailed quantitative segregation of the 000 budget into the mechanisms responsible for the changes at the bar-scale. The utility of both these methodological developments were tested on three different data sets representing event-based monitoring (Sulphur Creek, California), restoration monitoring (Mokelumne River, California), and annual-monitoring of a natural dynamic system (River Feshie, Scotland). One of the themes that emerges across the application of these tools in the three different settings is the sharp contrast between which geomorphological mechanisms . of change are dominant in areal versus volumetric terms. The tools extend what can reliably be inferred about geomorphological change from repeat topographic surveys.

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