The composition of seed banks of areas on the drained Kissimmee River floodplain (Florida, USA) that are currently pasture and formerly had been wet prairie, broadleaf marsh, and wetland shrub communities was compared to that of seed banks of areas that have extant stands of these communities. The species composition of the seed banks of existing wet prairie and former wet prairie sites were the most similar, with a Jaccard index of similarity of 55. Existing and former broadleaf marsh and wetland shrub communities had Jaccard indices of 38 and 19, respectively. Although existing and former wet prairie seed banks had nearly the same species richness, species richness at former broadleaf marsh and wetland shrub sites was higher than at existing sites. Mean total seed densities were similar in existing and former wet prairies (700 to 800 seeds m2). However, seed densities in former broadleaf marsh and wetland shrub sites were significantly greater than in comparable existing communities (>4,900 seeds m2 at former sites versus 200 to 300 in existing communities). The higher seed densities in former broadleaf marsh and wetland shrub sites was due to over 4,000 seeds m2 of Juncus effusus in their seed banks. Half of the species that characterize wet prairies were found in the seed banks at former and existing wet prairie sites. At existing broadleaf marsh and wetland shrub sites, most of the characteristic species were found in their seed banks. However, only one characteristic broadleaf species was found in the seed banks of the former broadleaf marsh sites, and no characteristic wetland shrub species were found in the seed banks of the former wetland shrub sites. The seeds of only two non-indigenous species were found in the seed banks of former wetland communities at very low densities. For all three vegetation types, but particularly for the broadleaf marsh and wetland shrub sites, re-establishment of the former vegetation on the restored floodplain will require propagule dispersal from off-site sources.

This dissertation aims to interpret the environmental factors which will inform land use planning for the Liesbeek-Black River Confluence Area. It is in partial fulfilment of the academic requirements for a Master of Philosophy (M.Phil) in Environmental Science through the Department of Environmental and Geographical Science (ENGEO) at the University of Cape Town (UCT). This document follows on from the Baseline Information Document (BID) produced by the 1994 Masters students and should be read in combination with that document. This dissertation uses the information provided in that document, and with the support of other materials and insights, draws conclusions for the most appropriate land use for the study area. A Statement of the Problem, the Aim, Approach and Philosophy adopted towards the Study Area in this Dissertation. The problem is perceived to be the substantial public objection to recent proposed developments in the study area. These objections have revolved around the method of disposal of State land, the fragmentation of public open space and the apparent disregard of the authorities for the natural historical legacy of the Cape Peninsula. The aim of the study is to demonstrate that the study area holds potential as a public amenity. This could be self-supporting and of benefit to future generations in the region and is therefore worthy of conservation. The approach adopted in this dissertation is that the study area is unsuitable for any use other than as a conservation and recreational reserve. This could prove its value in a substantially more populated and informed future Cape Town. Urban open space, which constitutes wildlife habitat, is required locally to meet increased human population habitation needs. This need is perceived to be global phenomenon. There is concern that the accumulated consequence of these local demands, will result in a profound negative effect on the Biosphere.

This dissertation is the individual analysis and evaluation of the baseline information on the Liesbeeck-Black River Confluence Area (hereinafter referred to as Confluence Area) gathered by the 1993-1994 Environmental and Geographical Science (EN GEO) Master of Philosophy (MPhil) class (see Appendix A). This dissertation is submitted to the examiners for evaluation as a partial requirement for the MPhil degree in Environmental Science. The baseline report (hereinafter BLR) is titled "Environmental Baseline Study for Land-Use Decision-Making in the Liesbeeck and Black River Confluence Area" (ENGEO Master's Class, 1994). It contains a comprehensive description, as well as preliminary analysis, of all the environmental components (socioeconomic and biophysical) that could be of relevance to land-use planning in the area. The overall need for this study, which comprises the group BLR and the individual dissertations, arises out of the fact that the Confluence Area with its river systems, is part of a "green, open space corridor" that is under pressure from development in a city needing to densify and contain urban sprawl. There is thus potential conflict between development and other environmental considerations including that of open space retention for conservation and recreation purposes. The Cape Town City Council (CCC) suggested this study but is not a "client". The study on the Confluence Area is intended to be of use to the CCC to enhance their ability to make sound land-use decisions for the area in the best interests of society at large. The CCC is also involved in numerous planning studies for the proposed redevelopment of a large tract of land adjacent to the study area, called the Culemborg-Black River area (hereinafter C-BR), and this study can feed into the overall planning process. This individual dissertation provides the CCC planning process with recommendations and land-use alternatives for the Confluence Area. Since the BLR forms the basis of this dissertation, they should be read in conjunction with each other.

Bibliography: pages 131-139. / The construction of bridge embankments and other physical obstacles in estuaries has often resulted in the redistribution of sediments, which ultimately leads to detrimental impacts in these environments. The aim of this study is to investigate how the sediment distribution and dynamics within a specific estuary, the Uilkraals estuary, have been affected by human disturbance; focusing on the impacts arising from construction of two temporary embankments and a permanent bridge and embankment. The Uilkraals estuary is situated in the south-western Cape, approximately 60 kilometres north-west of Cape Agulhas. Human impact has been extensive and engineering projects of various sizes and permanence have marked the recent history of this estuary. A bridge and embankment which cross the estuary 800 m from the mouth were built in 1973. In 1978 an embankment was built between the bridge and the estuary mouth. A second embankment which replaced the first in 1980, was removed before the end of that year. Extensive dune reclamation occurred on the left bank between 1938 and 1973. The techniques used in the study include: (i) a quantitative analysis of all available aerial photographs from 1938 to 1987 (ii) a ground survey and (iii) core and surface sediment sampling. The quantitative analysis reveals that the major changes in estuarine characteristics have been in response to human disturbance. The contour map and cross-sections drawn from the ground survey indicate a build-up of sediment downstream of the bridge and scouring of the channel upstream. The latter suggests the dominance of the flood-tidal current in the estuary. The core sediment analyses are unable to distinguish any real difference in the modes of sediment deposition on either side of the bridge embankment. The embankment has, however, affected deposition by acting as a "hydraulic shelter" to sediment accumulated downstream of the bridge during high run-off events and by initiating deposition of sediment upstream of the embankment. The surface sample analyses indicate that there has been an increase in flow velocities in the vicinity of the bridge since its construction and that the major agents which bring marine sediment into the estuary are flood-tidal currents and wind. It is concluded that the sediment distribution and dynamics of the Uilkraals estuary have been affected by human disturbance. Recommendations for future management of the estuary are that no further embankments should be constructed in the estuary and that the construction of a culvert or culverts under the existing bridge embankment would alleviate a number of problems presently experienced in the estuary.

Longitudinal profile , channel cross-section geometry, and depositional patterns of the Green River in its course through the eastern Uinta Mountains are each strongly influenced by river-level geology and tributary sediment delivery processes. We surveyed channel cross sections at 1-km intervals, mapped surficial geology , and measured size and characteristics of bed material in order to evaluate the geomorphic organization of the 70- km study reach . Canyon reaches that are of high gradient and narrow channel geometry are associated with the most resistant lithologies exposed at river level and the most frequent occurrences of tributary debris fans. Meandering reaches that are characterized by low gradient and wide channel geometry are associated with river-level lithology that is of moderate to low resistance and very low debris fan frequency. The channel is in contact with bedrock or talus along only 42 percent of the bank length in canyon reaches and there is an alluvial fill of at least 12 m that separates the channe l bed from bedrock at three borehole sites. The influence of lithology primarily operates through the presence of resistant boulders in debris fans that are delivered by debris flows from steep tributaries. The depositional settings created by debris fans consist of (1) channel-margin deposits in the backwater above the debris fan, (2) eddy bars in the zone of recirculating flow below the constriction, and (3) expansion gravel bars in the expansion below the zone of recirculating flow. These fan-eddy complexes are the storage location of about 70 percent, by area, of all fine- and coarse-grained alluvium contained within the canyons above the low-water stage. Immediately adjacent meandering reaches contain an order of magnitude more alluvium by area but have no debris fan-created depositional settings. This study also describes the flood-plain and terrace stratigraphy of the Green River in the eastern Uinta Mountains and changes due to the operations of Aarning Gorge Dam, upstream from the study area. These landforms are vertically aggrading deposits that are longiuidinally correlative throughout the 65-km study reach. The suite of surfaces identified includes a terrace that is inundated by rare pre- or post-dam floods, an intermediate bench that is inundated by rare post-dam floods, and a post-dam flood plain that is inundated by the post-dam mean annual flood. Analysis of historical photographs in the study reach shows that both the intermediate bench and post-dam flood plain are landforms that were not present in any of the 6 years for which photographs were examined between 1871 and 1954. Photographic replications also show that gravel bars consisting of bare gravel in 1922 and earlier photographs are now covered by fine-grained alluvium and vegetation. Decreased gravel-bar mobility is indicated by estimates of critical and average boundary shear stress. Comprehensive surficial geologic mapping of the study area indicates that the bankfull channel has decreased in width by an average of about 20 percent.

Environmental scientists increasingly use remotely-sensed images to measure how rivers develop over time and respond to upstream changes in environmental drivers such as land use, urbanization, deforestation and agricultural practices. These measurements are subject to uncertainty that can bias conclusions. The first step towards accurate interpretation of river channel change is properly quantifying and accounting for uncertainty involved in measuring changes in river morphology. In Chapter 2 we develop a comprehensive framework for quantifying uncertainty in measurements of river change derived from aerial images. The framework builds upon previous uncertainty research by describing best practices and context-specific strategies, comparing each approach and outlining how to best handle measurements that fall below the minimum level of detection. We use this framework in subsequent chapters to reduce the impact of erroneous measurements. Chapter 3 evaluates how the time interval between aerial images influences the rates at which river channels appear to laterally migrate across their floodplains. Multiple lines of evidence indicate that river migration measurements obtained over longer time intervals (20+ years) will underestimate the ‘true’ rate because the river channel is more likely to have reversed the direction of migration, which erases part of the record of gross erosion as seen from aerial images. If the images don’t capture channel reversals and periodic episodes of fast erosion, the river appears to have migrated a shorter distance (which corresponds to a slower rate) than reality. Obtaining multiple measurements over shorter time intervals (< 5 years) and limiting direct comparisons to similar time intervals can reduce bias when inferring how river migration rates may have changed over time. Chapter 4 explores the physical processes governing the relationship between river curvature and the rate of river migration along a series of meander bends. We used fine-scale empirical measurements and geospatial analyses to confirm theory and models indicating that migration and curvature exhibit a monotonic relationship. The results will improve models seeking to emulate river meander migration patterns.

The purpose of this study was to produce a detailed geologic map of the CRBG in the western portion of the Columbia River Gorge (fig. 1). The objectives were (1) to identify and delineate the extent of the Priest Rapids Member and Pomona Member intracanyon flows, and (2) to define the relationship of post-CRBG units to the CRBG intracanyon flows.

The Wind River gold prospect is located in TSN, R7E of Skamania County, Washington, and is an epithermal gold-quartz vein system hosted in volcanic rocks of the Ohanapecosh Formation, a late Eocene to middle Oligocene unit of calcalkaline chemical composition. Andesitic pyroclastic rocks of the Ohanapecosh Formation are the host of mineralization in the study area, and form the lowest of several stratigraphic subunits. These pyroclastic rocks are overlain by two sequences of lava flows which cap the ridges and are folded by an anticlinal warp over the length of Paradise Ridge, plunging gently to the southeast. Toward the west, the number of flows decreases and the proportion of intercalated pyroclastic rocks increases. Numerous dikes cut the pyroclastic rocks at the Wind River prospect. Geochemical data show these dikes to have been feeders for the overlying lava flows. Differing degrees of alteration of the dikes relative to the most intensely altered pyroclastic rocks which they cut indicates a complex history of overlapping hydrothermal and volcanic activity at the prospect.

Twenty--one morphological characters were measured in shrews from four islands in the Columbia River and from the adjacent Oregon and Washington shores. Information on the history and characteristics of the river islands was gathered to facilitate interpretation of the shrew’s morphology data. Significant differences between character means of different populations were detected and average taxonomic distances between pairs of populations were calculated. The Columbia River is an incomplete barrier to gene flow, but its influence has been sufficient to allow divergence of island populations. Natural selection on the small gene pools of island populations has probably contributed to the divergence. Shrews most likely reached the islands from the mainlands by rafting on floating vegetation and debris. Morphometric comparison of island populations seems to provide a more sensitive indication of restricted gene flow than similar comparison of opposite mainland populations.

Indiana University-Purdue University Indianapolis (IUPUI) / The late pre-Columbian period in the central Illinois River valley (CIRV) is demarcated by the development of large, often-fortified Mississippian towns, farming hamlets, extensive trade networks, and shifting political alliances between AD 1050 and 1450. The fission and fusion of local polities ceased with abrupt abandonment of the CIRV by AD 1450 as part of the larger Vacant Quarter phenomenon. Located on a hypothesized boundary between Mississippian and Oneota zones of socio-political influence during the 14th century, Star Bridge (11Br17) was a Mississippian village previously believed to have been incinerated during an assault. Through the analysis of an avocational surface collection, a 1992 excavation assemblage, and recent geophysical investigations, my research re-examines Star Bridge and assesses the site’s integrity after decades of agricultural modification. Geophysical data and the material culture from excavations suggest Star Bridge never burned but was abandoned after one or two generations of occupation shortly before the exodus of Mississippian and Oneota groups from the CIRV. Meanwhile, my analyses also revealed a dearth of Oneota-derived or influenced material culture, indicating a dearth of interaction between Star Bridge’s inhabitants and their neighbors upstream. Instead, the material culture suggests Star Bridge was part of a string of late 13th and 14th century villages known as the La Moine River polity.