The main objective of this work is to develop a quasi three-dimensional numerical model to simulate stony debris flows, considering a continuum fluid phase, composed by water and fine sediments, and a non-continuum phase including large particles, such as pebbles and boulders. Large particles are treated in a Lagrangian frame of reference using the Discrete Element Method, the fluid phase is based on the Eulerian approach, using the Finite Element Method to solve the depth-averaged Navier–Stokes equations in two horizontal dimensions. The particle’s equations of motion are in three dimensions. The model simulates particle-particle collisions and wall-particle collisions, taking into account that particles are immersed in a fluid. Bingham and Cross rheological models are used for the continuum phase. Both formulations provide very stable results, even in the range of very low shear rates. Bingham formulation is better able to simulate the stopping stage of the fluid when applied shear stresses are low. Results of numerical simulations have been compared with data from laboratory experiments on a flume-fan prototype. Results show that the model is capable of simulating the motion of big particles moving in the fluid flow, handling dense particulate flows and avoiding overlap among particles. An application to simulate debris flow events that occurred in Northern Venezuela in 1999 shows that the model could replicate the main boulder accumulation areas that were surveyed by the USGS. Uniqueness of this research is the integration of mud flow and stony debris movement in a single modeling tool that can be used for planning and management of debris flow prone areas.

Several laterally extensive candidate tsunami deposits are preserved along coastlines facing the eastern Java Trench, indicating it has experienced mega-thrust earthquakes in the past. We investigated 37 coastal sites in Bali, Lombok, Sumba and Timor islands, many of which preserve course sand and pebble layers that overlie sharp basal contacts with scour marks into the mud, fine upward in grain size, and have bimodal grain size distributions. Other unique features are the common occurrence of marine fossils and concentrations of heavy minerals. The occurrence of these high-energy deposits interlayered with clay-rich units indicates the coarse clastics are anomalous because they were deposited in what is normally a very low-energy depositional environment. The lateral extent and paucity of thin, coarse clastic layers with marine organisms are inconsistent with local stream flood event, and the proximity to the equator of the sites diminishes the possibility of marine flood events from cyclones. The sparse, but consistent, the occurrence of at least two candidate tsunami deposits at depths of 1 and 2 meters over 950 km along the strike of the Java Trench may reveal that mega-thrust earthquakes have occurred there and generated giant tsunamis in the recent past. Five widely scattered imbricated boulder deposits are also found on Bali, Lombok, and Sumba. The boulders consist of slabs of hardpan up to 2.5 m in length and 80 cm thick that was torn from a near-shore seabed and stacked on top of one another. Some of the boulders were carried over the erosional coastal bank and deposited up to 100 meters inland. Comparisons with imbricated boulder ridges formed during the 1994 tsunami in east Java indicate that these deposits are from one or multiple tsunamis sourced by the Java Trench. Experiments in effective ways to communicate and implement tsunami disaster mitigation strategies have led us to train local communities about the 20-20-20 rule. If coastal communities experience more than 20 seconds of shaking from an earthquake, even if it is not intense, they should evacuate the coast. The time delay between the earthquake and arrival of tsunami waves is around 20 minutes, which is the time window for evacuation. Some tsunami waves may be as high as 20 meters, which is the target elevation for evacuation. Adopting the 20-20-20 rule could save thousands of lives throughout the region, especially in Bali where nearly 1 million people inhabit likely tsunami inundation zones.

As public awareness of river degradation has grown in recent years, the number of stream restoration activities has increased dramatically. Anthropogenic influences at a range of spatial scales from watershed landuse to riparian vegetation management to local channel morphology can have hierarchical relationships to local (meso- and macro-) in-stream habitat characteristics. This research examined these influences first by examining the influence of complex channel morphology on meso-scale brook trout (Salvelinus fontinalis) habitat in Shenandoah National Park, VA, and then by examining the combined influence of watershed urbanization and riparian vegetation (100-200 m reaches) on stream temperature. Moving beyond one-dimensional (1D) averaged representations of fish habitat, this research explored the distribution of two-dimensional (2D) flow complexity metrics at the meso-habitat scale as explanatory variables for brook trout habitat preferences and as potential metrics to evaluate habitat restoration design. Spatial hydraulic complexity metrics, including area-weighted circulation and kinetic energy gradients, were calculated based on 2D depth averaged modeled velocity distributions in two 100-m reaches on the Staunton River. While there were no statistically significant correlations between kinetic energy gradients or area-weighted circulation and fish density, fish density was positively correlated to the percent of the channel dominated by protruding boulders. The structural complexity of areas with protruding boulders create complex flow patterns suggesting that flow complexity plays an important role in available brook trout habitat preferences at the local scale, although the 2D depth averaged model may not have adequately represented this complexity. The 2D distribution of flow characteristics was then investigated further to quantify areas of flow refugia (low velocity shelters) and the relationship between these areas, traditional measures of habitat quality, and fish biomass. Flow complexity in the vicinity of flow obstructions (in this case, boulders) was investigated further using patch classification and landscape ecology metrics. The relative influence of riparian vegetation on stream temperature (another important habitat characteristic) in urban and nonurban watersheds was investigated in 27 paired forested and nonforested reaches in PA, MD, and DE. Riparian vegetation and watershed-scale urbanization both influence stream temperature, which can have profound impacts on in-stream ecosystems. Generally, increased urbanization and removal of riparian forest influenced maximum stream temperatures resulting in higher maximum summer stream temperatures (up to 1.8°C); however, the influence of riparian forests (at at 100-200 m reach scale) decreased with increasing urbanization. Extreme maximum summer temperatures, which are a concern for aquatic biota, increased in both frequency and duration in urban nonforested reaches relative to forested reaches indicating that the addition of a forested 100-200 m long buffer partially mitigated these temperature extremes even in urban watersheds. Overall, changes to channel morphology and riparian vegetation had measurable local effects on stream habitat (temperature and hydraulic complexity) yet the implications of restoration efforts at the local scale on ecosystem services at a larger (km +) scale requires further study. / Ph. D.

Disturbances are ubiquitous features of most northern forest ecosystems. The subsequent response of plant assemblages on both short (resistance or not) and long term (recolonization or not) will depend on a number of factors operating at several spatial scales. In boreal forest ecosystems, bryophyte assemblages are a conspicuous and species rich group of plants for which these processes are poorly understood. Using a combination of experimental and observational approaches this thesis explores these questions for closed-canopy bryophyte assemblages in relation to a) microtopography (both for the initial and long-term response), b) environmental constrains during post-logging succession and c) disturbance type. My results clearly show that the shade and shelter provided by microtopographic surface structures can increase survival rates of bryophytes following clear-cut logging by decreasing mortality from microclimatic stress and mechanical disturbance. Following clear-cutting, the recovery of forest floor and dead wood living bryophytes seems to be a relatively steady and progressive process without any major bottleneck episodes in the young or semi-mature forest stages with much of the pre-disturbance composition recovered after 50 years. Although boulders were found to increase the initial survival on clear-cuts and hence increase disturbance resistance, we found no evidence that boulders influenced the subsequent recolonization process. Lastly, strong compositional dissimilarities were found in young forests (40 years) following clear-cut logging, wildfire and insect outbreak, indicating divergent trajectories to occur following different disturbances. Hence, early seral stages of forest ecosystems regenerating after natural disturbances seem to compliment young managed forests in maintaining landscape level diversity. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 3: Manuscript. Paper 4: Manuscript.

A boulder bed unit in the upper Haymond Formation (Pennsylvanian), generally believed to be olistostromes, is exposed in the eastern Marathon Basin, west Texas. Two localities of this unit (Housetop Mountain and Clark Butte) contain clasts derived from several formations found within the basin, as well as exotic Devonian metamorphic and volcanic rocks. This report describes a third previously unstudied site (Martin Ranch locality) that contains clasts of exotic Middle Cambrian shelf limestones. These limestones provide a key to the Early Paleozoic history of the Marathon region. The boulder beds lie in the upper part of the Haymond Formation. At the Martin Ranch locality they form a zone that is traceable for 6.6 km along strike and is up to 230 m thick. These boulder beds contain interbedded units of massive, unstratified, pebble- to boulder-bearing mudstone, thickly bedded, massive sandstone, lenses of pebbly sandstone, and deformed flysch beds. About 80 percent of the clasts found in the boulder beds at Martin Ranch are chert derived from several basin formations. Unique displaced slabs of bedded chert pebble conglomerate comprise about 10 percent of the clasts. Theses conglomerates were probably derived from upper fan-channel deposits within the lower Haymond Formation. Pennsylvanian limestone clasts redeposited from the basin facies of the Dimple Formation and clasts of exotic, late Middle Cambrian limestones each comprise about 5 percent of the clasts. These Cambrian limestones, older than any formation in the Marathon Basin, contain a fauna characteristic of the seaward edge of the cratonic carbonate shelf. The presence of the Cambrian clasts constrains the location of the North American shelf edge during the Cambrian, placing it at least 120 km southeast of the present day Marathon Basin. Both the Martin Ranch and Housetop Mountain boulder beds are composed mainly of clast-bearing, matrix-supported mudstone which have pebbly sandstone, massive sandstone, and flysch beds interstratified with the mudstone and represent periodic deposition of debris flows, slumps, slides, and turbidites interspersed with normal basin deposition of flysch facies rocks. However, different clast types are found at the two localities. The Martin Ranch locality has clasts of Cambrian limestone and chert pebble conglomerate, the latter up to 90 m in length, that are absent at the other localities. Exotic Pennsylvanian limestone clasts and exotic Devonian metamorphic and volcanic rocks, common at Housetop Mountain, are rare or missing at Martin Ranch. The Clark Butte locality is unique because it lacks the mudstone which dominates the other two localities. Instead, the matrix is composed of a pebbly sandstone and conglomerate associated with thick sandstone beds. The boulder beds at this locality may represent upper fan channels and channel-lag deposits. The turbidites and olistostromes resulted from recycling of the southern edge of the tectonic basin as the advancing Ouachita thrusts uplifted the pre Haymond strata. Most of the clasts were from older basin formations exposed by these faults; however one of these thrusts also uplifted slivers of exotic Middle Cambrian limestone. Earthquakes probably triggered slumps and rock falls off the fault scarps. As the boulders travelled downslope plowing through the slope sediments, they accumulated more material. This combination of slide debris and slope mud turned the slumps and slides into debris flows. Between episodes of debris flows and turbidity currents, normal basin deposition of thinly bedded turbiditic sandstone and pelagic shale occurred. / text

With the growing trend of construction, the demand for building materials is growing steadily. Porous concrete is widely used in the building industry, that makes efforts to discount production and simultaneously save the environment. The aim of this thesis is to develop high-quality porous concrete by using alternative raw materials as a substitute for silicate sand. As a possible substitute were chosen: Silica masonry, foundry sand and fireclay boulders. The influence of two key parameters - the specific surface (130, 240 and 350 m2·kg-1) and the amount of silica sand substitution (10, 30 and 50 %) were monitored. Two autoclaving modes (7 and 12 hours of isothermal durations at 190 ° C) were tested. Based on the physico-mechanical and mineralogical characteristics of the porous concrete composites was chosen the ideal surface area of 240 m2·kg-1 and time of isothermal endurance was determined at 7 hours (temperature 190 ° C, pressure 1,4 MPa). From the optimal intentions were created samples with a macroporous structure, using an aluminum powder. Physical-mechanical properties and microstructural analysis (XRD, SEM) were subsequently determined on the samples. Ideal recipes were proposed with 50% sand substitution of fireclay boulders and 10% substitution of foundry sand. This was due to a 10% higher compressive strenght and an increase of the coefficient of constructiveness, compared to the reference sample.

This dissertation investigates how a symmetrical approach to archaeology can be applied to identify the properties and effects of the non-living, abiotic materials. And to reconfigure the relationship between humans and non-human objects, bridging the divide between what has been termed ‘cultural’ and ‘natural’ and thus placed in different ontological realms. This is examined by studying the practices surrounding “boulder graves”, from the Late Bronze Age - Early Iron Age (approx. 1000 – 0 BC) in Kättsta, Ärentuna parish in Uppland, Sweden. The boulders tend to be studied from an anthropocentric point of view, in which they are seen primarily as passive objects, interpreted only for what they represent. The objective of this research, however, is to gain new insights into the agency of boulders, and how they contributed to the practices carried out adjacent to them. The dissertation is based on a case study where a thematic analysis is performed, focusing on the properties and characteristics of boulders, their affordances, the distribution of finds and their interrelations, and the effects their relations generated. The results show that the boulders themselves contributed in human-stone relations and were vital in the formation of the grave-like features they became part of. It is argued that a symmetrical, non-anthropocentric approach to these features will broaden our view on materialities in the past, affording ontological as well as ecological implications.