Slope basins, headless canyons, and submarine palaeoseismology of the Cascadia accretionary complex

A combination of geomorphological, seismic reflection and geotechnical data constrains this study of sediment erosion and deposition at the toe of the Cascadia accretionary prism. We conducted a series of ALVIN dives in a region south of Astoria Canyon to examine the interrelationship of fluid flow and slope failure in a series of headless submarine canyons. Elevated head gradients at the inflection point of canyons have been inferred to assist in localized failures that feed sediment into a closed slope basin. Measured head gradients are an order of magnitude too low to cause seepage-induced slope failure alone; we therefore propose transient slope failure mechanisms. Intercanyon slopes are uniformly unscarred and smooth, although consolidation tests indicate that up to several metres of material may have been removed. A sheet-like failure would remove sediment uniformly, preserving the observed smooth intercanyon slope. Earthquake-induced liquefaction is a likely trigger for this type of sheet failure as the slope is too steep and short for sediment flow to organize itself into channels. Bathymetric and seismic reflection data suggest sediment in a trench slope basin between the second and third ridges from the prism's deformation is derived locally. A comparison of the amounts of material removed from the slopes and that in the basin shows that the amount of material removed from the slopes may slightly exceed the amount of material in the basin, implying that a small amount of sediment has escaped the basin, perhaps when the second ridge was too low to form a sufficient dam, or through a gap in the second ridge to the south. Regardless, almost 80% of the material shed off the slopes around the basin is deposited locally, whereas the remaining 20% is redeposited on the incoming section and will be re-accreted.
     

Critical Zone Assessments of an Alluvial Aquifer System Using the Multi-influencing Factor (MIF) and Analytical Hierarchy Process (AHP) Models in Western Iran

Natural Resources Research - Many arid regions in the world suffer from over-exploitation of local groundwater resources leading to the degradation of freshwater aquifer systems, drying of spring...     

Comparing performance of different loss methods in rainfall-runoff modeling

Water Resources - With respect to the effect of precipitation loss on runoff generation, different loss methods of Soil and Conservation Service (SCS), Green and Ampt (G.A.), Initial-Constant...     

Shear Strength Development with Burial in Eel River Margin Slope Sediments

As part of the STRATAFORM project, a series of cores were obtained from the Eel River Margin area of Eureka, California. The geotechnical analysis of intact specimens and of reconstituted samples provides some insight on the development of shear strength with burial. The results show the effect of bioturbation in the early part of the lifetime of a sediment. SEDCON tests were used to proposed various relationships which help predict the changes in density, liquidity index, and strength as a function of depth. These relationships are found useful from near the water sediment-interface down to a depth of at least 400 m in the sediment column.     

Identification of hydrothermal alteration minerals associated with geothermal system using ASTER and Hyperion satellite data: a case study from Yankari Park,NE Nigeria

Concealed and fossilized geothermal systems are not characterized by obvious surface manifestations like hotsprings and fumaroles, therefore, could not be easily identifiable using conventional techniques. In this investigation, the applicability of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Hyperion data-sets were evaluated in discriminating hydrothermal alteration minerals associated with geothermal systems as a proxy in identifying subtle Geothermal systems at Yankari Park, Nigeria. Feature-oriented principal component selection, spectral angle mapper, linear spectral unmixing were applied to ASTER data based on spectral characteristics of hydrothermal alteration key minerals for a systematic selective extraction of the information of interest. Analytical imaging and geophysics-developed processing methods were applied to Hyperion data for mapping iron oxide/hydroxide minerals and clay mineral assemblages in hydrothermal alteration zones. The results indicate that ASTER and Hyperion could be complemented for reconnaissance stage of targeting subtle alteration mineral assemblages associated with geothermal systems.     

Evaluation of ICA and CEM algorithms with Landsat-8/ASTER data for geological mapping in inaccessible regions

Many regions remain poorly studied in terms of geological mapping and mineral exploration in inaccessible regions especially in the Arctic and Antarctica due to harsh conditions and logistic difficulties. Application of specialized image processing techniques is capable of revealing the hidden linear mixing spectra in multispectral and hyperspectral satellite images. In this study, the applications of Independent component analysis (ICA) and Constrained Energy Minimization (CEM) algorithms were evaluated for Landsat-8 and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) remote sensing data for geological mapping in Morozumi Range and Helliwell Hills areas, Northern Victoria Land (NVL), Antarctica. The results of this investigation demonstrate the capability of the two algorithms in distinguishing pixel and subpixel targets in the multispectral satellite data. The application of the methods for identifying poorly exposed geologic materials and subpixel exposures of alteration minerals has invaluable implications for geological mapping and mineral exploration in inaccessible regions.     

Ten best practices to strengthen stewardship and sharing of water science data in Canada

Water science data are a valuable asset that both underpins the original research project and bolsters new research questions, particularly in view of the increasingly complex water issues facing Canada and the world. Whilst there is general support for making data more broadly accessible, and a number of water science journals and funding agencies have adopted policies that require researchers to share data in accordance with the findable, accessible, interoperable, reusable (FAIR) principles, there are still questions about effective management of data to protect their usefulness over time. Incorporating data management practices and standards at the outset of a water science research project will enable researchers to efficiently locate, analyse and use data throughout the project lifecycle, and will ensure the data maintain their value after the project has ended. Here, some common misconceptions about data management are highlighted, along with insights and practical advice to assist established and early career water science researchers as they integrate data management best practices and tools into their research. Freely available tools and training opportunities made available in Canada through Global Water Futures, The Gordon Foundation DataStream, the Digital Research Alliance of Canada Portage Network, Compute Canada, and university libraries, among others are compiled. These include webinars, training videos, and individual support for the water science community that together enable researchers to protect their data assets and meet the expectations of journals and funders. The perspectives shared here have been developed as part of the Global Water Futures programme's efforts to improve data management and promote the use of common data practices and standards in the context of water science in Canada. Ten best practices are proposed that may be broadly applicable to other disciplines in the natural sciences and can be adopted and adapted globally.     

Landslide Mapping and Assessment by Integrating Landsat-8, PALSAR-2 and GIS Techniques: A Case Study from Kelantan State,Peninsular Malaysia

Integration of satellite remote sensing data and GIS techniques is an applicable approach for landslide mapping and assessment in highly vegetated regions with a tropical climate. In recent years, there have been many severe flooding and landslide events with significant damage to livestock, agricultural crop, homes, and businesses in the Kelantan river basin, Peninsular Malaysia. In this investigation, Landsat-8 and phased array type L-band synthetic aperture radar-2 (PALSAR-2) datasets and analytical hierarchy process (AHP) approach were used to map landslide in Kelantan river basin, Peninsular Malaysia. Landslides were determined by tracking changes in vegetation pixel data using Landsat-8 images that acquired before and after flooding. The PALSAR-2 data were used for comprehensive analysis of major geological structures and detailed characterizations of lineaments in the state of Kelantan. AHP approach was used for landslide susceptibility mapping. Several factors such as slope, aspect, soil, lithology, normalized difference vegetation index, land cover, distance to drainage, precipitation, distance to fault, and distance to the road were extracted from remotely sensed data and fieldwork to apply AHP approach. The excessive rainfall during the flood episode is a paramount factor for numerous landslide occurrences at various magnitudes, therefore, rainfall analysis was carried out based on daily precipitation before and during flood episode in the Kelantan state. The main triggering factors for landslides are mainly due to the extreme precipitation rate during the flooding period, apart from the favorable environmental factors such as removal of vegetation within slope areas, and also landscape development near slopes. Two main outputs of this study were landslide inventory occurrences map during 2014 flooding episode and landslide susceptibility map for entire Kelantan state. Modeled/predicted landslides with a susceptible map generated prior and post-flood episode, confirmed that intense rainfall throughout Kelantan has contributed to produce numerous landslides with various sizes. It is concluded that precipitation is the most influential factor for landslide event. According to the landslide susceptibility map, 65% of the river basin of Kelantan is found to be under the category of low landslide susceptibility zone, while 35% class in a high-altitude segment of the south and south-western part of the Kelantan state located within high susceptibility zone. Further actions and caution need to be remarked by the local related authority of the Kelantan state in very high susceptibility zone to avoid further wealth and people loss in the future. Geo-hazard mitigation programs must be conducted in the landslide recurrence regions for reducing natural catastrophes leading to loss of financial investments and death in the Kelantan river basin. This investigation indicates that integration of Landsat-8 and PALSAR-2 remotely sensed data and GIS techniques is an applicable tool for Landslide mapping and assessment in tropical environments.     

Shear Strength Development with Burial in Eel River Margin Slope Sediments

As part of the STRATAFORM project, a series of cores were obtained from the Eel River Margin area of Eureka, California. The geotechnical analysis of intact specimens and of reconstituted samples provides some insight on the development of shear strength with burial. The results show the effect of bioturbation in the early part of the lifetime of a sediment. SEDCON tests were used to proposed various relationships which help predict the changes in density, liquidity index, and strength as a function of depth. These relationships are found useful from near the water sediment-interface down to a depth of at least 400 m in the sediment column.     

Clay-mineral suites,sources, and inferred dispersal routes: Southern California continental shelf

Clay mineralogy is useful in determining the distribution, sources, and dispersal routes of fine-grained sediments. In addition, clay minerals, especially smectite, may control the degree to which contaminants are adsorbed by the sediment. We analyzed 250 shelf sediment samples, 24 river-suspended-sediment samples, and 12 river-bed samples for clay-mineral contents in the Southern California Borderland from Point Conception to the Mexico border. In addition, six samples were analyzed from the Palos Verdes Headland in order to characterize the clay minerals contributed to the offshore from that point source. The <2 microm-size fraction was isolated, Mg-saturated, and glycolated before analysis by X-ray diffraction. Semi-quantitative percentages of smectite, illite, and kaolinite plus chlorite were calculated using peak areas and standard weighting factors. Most fine-grained sediment is supplied to the shelf by rivers during major winter storms, especially during El Ni?o years. The largest sediment fluxes to the region are from the Santa Ynez and Santa Clara Rivers, which drain the Transverse Ranges. The mean clay-mineral suite for the entire shelf sediment data set (26% smectite, 50% illite, 24% kaolinite+chlorite) is closely comparable to that for the mean of all the rivers (31% smectite, 49% illite, 20% kaolinite+chlorite), indicating that the main source of shelf fine-grained sediments is the adjacent rivers. However, regional variations do exist and the shelf is divided into four provinces with characteristic clay-mineral suites. The means of the clay-mineral suites of the two southernmost provinces are within analytical error of the mineral suites of adjacent rivers. The next province to the north includes Santa Monica Bay and has a suite of clay minerals derived from mixing of fine-grained sediments from several sources, both from the north and south. The northernmost province clay-mineral suite matches moderately well that of the adjacent rivers, but does indicate some mixing from sources in adjacent provinces.