This study qualitatively and quantitatively analyzes the geomorphology of alluvial fans in the Guadalupe Mountains Region (GMR) of west Texas and south-central New Mexico. Morphometric data for 31 alluvial fans and drainage basins ha ve been derived. The data set was subdivided into Guadalupe and Brokeoff Mountain fans and was further subdivided on the basis of their location along the two mountain ranges. A conventional morphometric analysis was conducted relating alluvial fan area and slope to drainage basin area in order to understand if and to what extent the alluvial fans of the GMR are dependent on the physical environment, including characteristics and processes of the drainage basin and depositional site. The results of the morphometric analysis indicate that the morphometric relationships that exist between the alluvial fans of the GMR and their contributory drainage basins are comparably to those of alluvial fans of the western United States. Morphologic and morphometric differences between the various groups primarily reflect geographic differences in the physiography and lithology of the contributory drainage basin, tectonics, and the various physical constraints imposed by the GMR.

The study focuses on the adjacent Tenthill and Ma Ma catchments which converge onto the heavily cultivated alluvial plain of Lockyer Creek. Groundwater extracted from the alluvial aquifers is the primary source of water for intensive irrigation. Within the study the hydrogeology is investigated, a conceptual groundwater model produced and a numerical groundwater flow model is developed from this. The hydrochemistry and stable isotope character of groundwater are also investigated to determine processes such as recharge and evaporation. Examination of bore logs confirms the Quaternary alluvium comprises a laterally continuous gravel aquifer with an average thickness of 4.5 m, overlain by mixed sands and clays which form a semi-confining layer with an average thickness of 22 m. Variations in long term groundwater hydrographs indicate the aquifer changes from confined to unconfined in some locations as water levels drop, while bores adjacent to creek banks display a rapid response to a flood event. Pump testing of bores screened in the gravel produces estimates of hydraulic conductivity ranging from 50-80 m/day and storativity of 0.00166 which are both within realistic bounds for this aquifer material. Major ion chemistry of surface water collected during a flood is Mgdominated, similar to alluvial groundwater in the Tenthill catchment and the Lockyer plain, suggesting a strong connection between surface and groundwater in these locations. Alluvial groundwater salinity in Tenthill catchment is typically less than 3500 ìS/cm but may approach 6000ìS/cm on the Lockyer plain. By contrast Ma Ma catchment alluvial groundwater is Na-dominated with conductivity up to 12000 ìS/cm and more associated with groundwater from the underlying sandstone bedrock. Stable isotope analyses of alluvial groundwater from throughout both catchments and the Lockyer plain are compared with basalt and sandstone groundwater. A range of processes have been identified including recharge to alluvium from basalt groundwater and evaporated surface water; and alluvial-bedrock groundwater mixing at some locations. Integration of the components of the study enabled the production of a conceptual hydrogeological model of the Lockyer alluvial plain, proposing two hydrostratigraphic units; the gravel aquifer and the overlying mixed sand and clay which acts as a semi confining unit. Hydrochemical and stable isotopic evidence suggests seepage from creek channels as the dominant recharge process. A single layer groundwater flow model using MODFLOW was developed, based on groundwater extraction data, to represent flow in the gravel aquifer. The model was calibrated to transient conditions with groundwater fluctuations, incorporating both drought and flood conditions. A sensitivity analysis for each of the aquifer properties demonstrates the model is insensitive to variations within realistic bounds for the gravel aquifer material, however, the model is highly sensitive to changes in the chosen boundary conditions. Predictive simulations with several annual extraction scenarios ranging from 1.75 to 0.5 ML/ha indicate the resulting minimum saturated aquifer thickness ranges from 0.03 to 1.4 m.

Debris-flows pose serious hazards to communities in mountainous regions of the world and are often responsible for loss of life and damages to infrastructure. Characterised by high flow velocity, large impact forces and long runout, debris-flows have potential discharges several times greater than clear water flood discharges and possess much greater erosive and destructive potential. In combination with poor temporal predictability, they present a significant hazard to settlements, transport routes and other infrastructure located at the drainage points (fan-heads) of watersheds. Thus, it is important that areas vulnerable to debris-flows are identified in order to aid decisions on appropriate land-uses for alluvial fans. This research has developed and tested a new GIS-based procedure for identifying areas prone to debris-flow hazards in the Coromandel/Kaimai region, North Island, New Zealand. The procedure was developed using ESRI Arc View software, utilising the NZ 25 x 25 m DEM as the primary input. When run, it enabled watersheds and their associated morphometric parameters to be derived for selected streams in the study area. Two specific parameters, Melton ratio (R) and watershed length were then correlated against field evidence for debris-flows, debris-floods and fluvial processes at stream watershed locations in the study area. Overall, strong relationships were observed to exist between the evidence observed for these phenomena and the parameters, thus confirming the utility of the GIS procedure for the preliminary identification of hydrogeomorphic hazards such as debris-flow in the Coromandel/Kaimai region study area. In consideration of the results, the procedure could prove a useful tool for regional councils and CDEM groups in regional debris-flow hazard assessment for the identification of existing developments at risk of debris-flow disaster. Furthermore, the procedure could be used to provide justification for subsequent, more intensive local investigations to fully quantify the risk to people and property at stream fan and watershed locations in such areas.

Thesis (M.S. - Geosciences)--University of Arizona. / Includes bibliographical references (leaves 43-45).

Thesis (Ph. D)--University of Washington, 1994. / Vita. Includes bibliographical references (leaves [191]-203).

Thesis (M.S.)--West Virginia University, 1999. / Title from document title page. Document formatted into pages; contains ix, 61 p. : ill. (some col.), maps (some col.) Includes abstract. Includes bibliographical references (p. 55-59).

Thesis (Ph.D.)--University of Wollongong, 2005. / Typescript. Includes bibliographical references: p. 245-386.

155 pages / In the stratigraphic record of Camp Creek are episodes of fluvial scour and fill thousands of years old. Radiocarbon dates and the Mazama tephra, which serves as a stratigraphic time line, temporally bracket episodes of vertical aggradation and incision. Before 9000 years B.P. the valley floor was scoured to the Tertiary bedrock. Aggradation dominated since that time. Large cut-and-fill structures indicate that two periods of erosion occurred prior to incision of the modern arroyo. The first occurred before 6800 yr B.P. and the second occurred approximately 3000 years ago. The modern arroyo-channel flows at or near the Tertiary bedrock, is entrenched as much as nine meters in the valley-fill alluvium and is thought to have originated during the late 19th century.

The objective of this review is to summarise the characteristics, significance and evolution of heavy minerals and their accumulations, and to identify the key controls on the development and distribution of heavy mineral concentrations in alluvial systems. These controls can be broadly classified as tectonic setting, geomorphic setting and grain-scale concentrating processes, each of which is discussed. Based on this review, exploration models are developed which are designed to indicate favourable localities for the accumulation of heavy minerals, and trends likely to be exhibited within these accumulations. The models are structured from the broadest scale of target selection, down to the local scale of sample site selection. The major conclusion of this work is that an understanding of process geomorphology is required to develop genetic models of placer development, including a detailed evaluation of climatic fluctuations throughout the Caenozoic. Palaeoplacers such as the Witwatersrand goldfield, are inferred to have formed under similar circumstances of tectonic setting as genetically comparable Caenozoic placers such as those of Otago, New Zealand. The means of preservation of such major basins is however poorly understood.

The Golo River in Corsica, France, is a short, steep river (~95 km, 2706 m relief) in the Western Mediterranean with formerly glaciated headwaters. The small size and location of the Golo River make this system ideal for observing the influence of climate and sea-level change on river dynamics over the 100,000 years. A rapidly advancing dating technique, optically stimulated luminescence, was utilized to determine the timing of these river deposits on the coastal plain in order to frame them in the context of previous glacial and interglacial episodes. Climate fluctuations in the headwaters supplied the vast majority of sediment into the system during glacial time periods, which was then transported and deposited near the mouth of the Golo River on the coastal Marana Plain. Sea- level also played a vital role in defining a geometric configuration that ultimately governed whether large amounts of sediment stored onshore or offshore. Analysis of the Golo River longitudinal profile and watershed reveals changes in steepness and gradient that are related to changes in rock type, fault movement and tectonically-driven base-level fall.