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Basin analysis and sequence stratigraphy a review, with a short account of its applicability and utility for the exploration of auriferous placers in the Witwatersrand BasinVan Eeden, Johan January 1996 (has links)
The Witwatersrand basin is unique in terms of its mineral wealth. The gold in the Witwatersrand basin is mainly concentrated in the placers and two types of unconformities are associated with the placer formation. This paper attempts to quantitatively describe the origin and depositional process of placers within the context of basin analysis, geohistory and sequences stratigraphic framework. Several tectonic models have been proposed for the evolution of the Witwater~rand basin and it seems as if a cratonic foreland basin accounts for many of the observed features observed the Central Rand Group basin. The tectonic subsidence curve generated for the Witwatersrand Basin clearly implies foreland basin response which was superimposed an older, deep seated extensional basin. These compressive tectonics can be superimposed on extensional basins, where the shift from extensional to compressional tectonics lead to inversion processes. The critical issues about the Witwatersrand basin which were addresed in this review, is the validity of basin wide correlation of placer unconformuties and whether sequence stratigraphy is applicable to fluvial systems of the Witwatersrand sequence. It is believed that the Central Rand Group was deposited as alluvial - fan deltas by fluvially dominated, braidplain systems with minor marine interaction which had a considerable impact on the preservation of economically viable placers. Most important to the exploration geologist is the recognition of stacking patterns of the fluvial strata to determine change in the rate at which accommodation was created. Identifying sequence boundaries and other relevant surfaces important for identifying these stacking patterns of the sequences, depends entirely on the recognition of a hierarchy of stratal units including beds, bedsets, parasequences, parasequence sets and the surfaces bounding sequences. Placers are closely associated with the development of disconformities and therefore become important to recognise in fluvial strata. If these placers are to become economic, the duration of subaerial exposure of the unconformities that allowed the placers to become reworked and concentrated must be determined. In order to preserve the placer, a sudden marine transgression is necessary to allow for minimal shoreline reworking and to cap the placer to prevent it from being dispersed. The placers in the Witwatersrand basin occur in four major gold-bearing placer zones in the Central Rand Group. Accordingly they can be assigned to four supercycles, which are cyclical and therefore predictive. It is the predictive nature of these rocks and the ability of sequence stratigraphy to enhance this aspect, which is a pre-requisite for an effective exploration tool in the search for new ore bodies or their extension in the Witwatersrand basin.
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Temporal patterns in the normal-regime fine-sediment cascade in Russell Creek Basin, Vancouver IslandNistor, Craig 05 1900 (has links)
Large, infrequent "episodic" sediment transfers are commonly considered differently from
"normal-regime" sediment-transfer activity. For example, in the important hillslope-gully-stream
sediment cascade pathway in coastal British Columbia, debris slides and debris torrents are
considered as "episodic events". On the other hand, lower-magnitude hillslope to gully-channel
sediment transfers and fluvial sediment tranSport within gully and stream channels are usually
considered as "normal-regime" activity, represented by annual yields. However, the results of this
study illustrate the highly episodic nature of normal-regime fine-sediment transfers, which are
closely linked to hydrometeorological and sediment-supply conditions. The results indicate that
qualitative modelling of fine-sediment transfer activity, at the synoptic or event scale, should be
possible based upon hydrometeorological and sediment-supply information. From such a model ~
the elements of which are presented in the concluding chapter ~ fine-sediment transfer activity
could be forecast based upon regional weather forecasts.
The study was conducted in Russell Creek Basin, on northern Vancouver Island, British
Columbia. Fine-sediment transfer activity was monitored at a nested hierarchy of sites
representing fine-sediment transfers from unstable hillslopes to a gully channel, suspended
sediment transport out of the unstable gully and a nearby stable gully, and suspended sediment
transport in Russell Creek near the mouth.
Russell Creek Basin is located within Tsitika Watershed, which is the site of a British
Columbia Ministry of Forests study dedicated to determining relative fine-sediment contributions
from natural and logging-related sediment sources. The results of the Russell Creek study
indicate that an event-based sediment sampling program is desirable and that at least some
automated sampling is required. Furthermore, development of a qualitative sediment-transfer activity forecast model would be useful in interpretation of sample data and would allow efforts to
be concentrated during the periods of greatest sediment-transfer activity. / Arts, Faculty of / Geography, Department of / Graduate
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The spatial variation of bed material texture in coupled basins on the Queen Charlotte IslandsRice, Stephen Philip January 1990 (has links)
Whether one is interested in the geomorphology, hydrology, or ecology of a river, the nature of the bed sediments is of major importance. Despite a long history of interest our ability to predict local grain size is poor, which is unfortunate given the labour and costs associated with bed material sampling. A preliminary model of sediment texture variation at the drainage basin scale, which makes a fundamental distinction between coupled and uncoupled hillslope-channel units, is presented.
It is hypothesised that grain size variations in strongly coupled rivers are unstructured as a result of overbank colluvial inputs and special storage elements. These preclude the development of the systematic downstream structure commonly associated with fluvial sorting and abrasion processes in uncoupled channels. This conjecture is assessed empirically using data collected in two rivers on the Queen Charlotte Islands.
It is found that distance alone does not explain changes in grain size, and that local variations are dominated by large organic debris jams. Impermeable jams are associated with upstream fining and downstream coarsening but the effect diminishes as the jams become more permeable, often with age. Jam placement is random, but frequent, and consequently at the drainage basin scale, grain size changes dramatically and unpredictably over very short distances. No deterministic structure is apparent.
Further analysis reveals that the observed variations of surface median grain size and Fredle index are best regarded as stochastic phenomena. Sampling criteria are then determined which enable the accurate characterisation of such variation, once a stream has been classified by land use and position relative to hillslopes. / Arts, Faculty of / Geography, Department of / Graduate
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Hydrology and water quality analysis in the Big Black River watershed, MississippiShabbir, Moniba 10 December 2021 (has links) (PDF)
Evaluating hydrology and water quality for the Big Black River Watershed in Mississippi was accomplished by using the Better Assessment Science Integrating Point and Nonpoint Source (BASINS 4.5), Loading Simulation Program in C++ (LSPC), and Water Quality Analysis Simulation Program (WASP) models. The watershed model calibration was originally accomplished by using historical data collected from U.S. Geological Survey (USGS). The watershed model was calibrated using data from 2000 through 2018 in order to quantify stream flow and point source discharges under a variety of hydrologic conditions. The model predicted response of hydrology was consistent with the observed data range. The hydrology part of the model was integrated for water quality simulation. Nutrients levels in the river systems were closely examined, without the impacts from point source discharges. The calibrated model could be used as a planning tool to assess the water quality and to calculate total maximum daily load (TMDL) in the nation’s watersheds.
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IMPACTS OF LAND USE/LAND COVER AND SOIL ON WATER QUALITY IN THE UPPER LITTLE MIAMI RIVER SUB-BASIN THE UPPER LITTLE MIAMI RIVER SUB-BASINAkshaya, Devendra Kumar 27 April 2012 (has links)
No description available.
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An evaluation of flexible pavement performance on the basis of deflection basins using illipave programDarmstater, Suzanna January 1989 (has links)
No description available.
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Exfiltration from Stormwater Ponds in Central FloridaAndreyev, Nicolas E. 01 January 1985 (has links) (PDF)
The objective of this study is to develop guidelines for the analysis of storm water retention ponds in Central Florida. Development of a combined seepage analysis considering both unsaturated and saturated groundwater flow incorporation into a systematic approach for storm water retention pond design will result in safer and more economical storm water management practices. The research was conducted in four phases: 1) A literature review. 2) A review of mathematical and empirical analysis of transient – unsaturated/saturated groundwater flow. 3) Construction and testing of a downscaled storm water pond model. 4) Incorporation of full scale percolation pond test data from ponds constructed and tested in Central Florida. The literature review was undertaken to research mathematical and empirical equations for both unsaturated and saturated groundwater seepage to be incorporated into the modelling and development of final system analysis. The review was concentrated on seepage studies conducted in subsoil conditions similar to those in Central Florida. It was found in the early review of literature that separate studies and modelling for unsaturated and saturated seepage are widespread and relatively well documented. However, documentation of combined groundwater seepage model, since the majority of storm water retention ponds in Central Florida experience both seepage condition (unsaturated/saturated) during the design storm event. Inspection of operational seepage ponds and interviews with regulatory agencies and consulting firms in Central Florida indicated that successful design of storm water retention ponds greatly depends on the accurate definition of the subsoil conditions and the seepage characteristics during a specific design storm event. Interviews with those responsible for pond design revealed that there is currently no widespread accepted design method, and most of the designs are based on mostly local experience. Also, history indicates that even though the unsteady seepage analysis is a complex phenomenon, there is usually very little money I the budget for its analysis and design. However, due to continuous increase of property values and the need to optimize pond sizing, the trend of under budgeting for seepage bond design is reversing. Application of the research results will yield a more accurate analysis which accounts for unsaturated and saturated seepage for sizing of storm water retention ponds in Central Florida. The analytical solutions developed from this research are a combination of acceptable mathematical and empirical groundwater seepage equations or dimensionless graphs modified for the purpose of storm water retention pond analysis.
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Filtration of Detained Stormwater through Sand and Alum Sludge for Water Quality ControlCassagnol, Claude L. 01 July 1980 (has links) (PDF)
Stormwater detention systems as they are frequently designed do not provide good water quality control of stormwater runoff. A filtration media to be used in conjunction with detention ponds to improve their pollutant removal efficiencies was tested at the University of Central Florida and found to be effective. The filtration media, which consisted of a mixture of sand and alum sludge, substantially improved effluent water quality. Average reductions of over 80 % were observed in concentrations of dissolved orthophosphorus, total orthophosphorus and total phosphorus. Reductions were also experienced in iron, aluminum, copper and zinc concentrations. A prototype filtration model is presently being tested on the Lake Eola watershed in Orlando, Florida. A stormwater management and design aid computer program originally written by Tim Curran (Curran 1980) to calculate stormwater hydrographs and retention volumes, and updated by the author to also calculate detention volumes will incorporate results from the prototype study.
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Transformation of Nitrogen in Highway Runoff Management SystemsTolbert, Robert D. 01 January 1984 (has links) (PDF)
The operation and maintenance of highways contributes a variety of pollutants to surface and subsurface waters. Solids, heavy metals, nutrients, oil and grease, pesticides and bacteria can all be associated with highway runoff. Although the full extent of the effect of all of these runoff constituents upon the quality of surrounding waters is not well defined, this study will mainly concentrate on nutrient contaminants (essentially nitrogen). The last decade has seen increasing efforts in research and development to abate contaminant discharges from highway runoff using a number of treatment facilities such as retention/detention basins, swales and wetland systems. An evaluation of the effectiveness of these systems in removing nitrogen by physical, chemical and biological uptake is the aim of this research endeavor. This information could prove invaluable in an overall assessment of the effectiveness of highway runoff treatment systems.
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A comparison of the pollutant removal efficiencies of retention and detention stormwater control basinsFesko, Steven F. January 1983 (has links)
This study analyzed data that had been previously collected by the Occoquan Watershed Monitoring Laboratory under the National Urban Runoff Program, to obtain an understanding of the degree of treatment of stormwater runoff obtainable in retention (maintains a water pool) and detention (drains completely) basins. Three basins were studied, two retention and one detention, and a total of 191 storm events were monitored using automatic sampling equipment. The samples were analyzed by the laboratory for COD, all nitrogen forms, all phosphorus forms, total suspended solids, and heavy metals (iron, manganese, etc.).
It was concluded that detention and retention ponds achieve substantial reduction in the pollutant loads carried by stormwater runoff from residential areas. Non-soluble settleable materials were removed to a comparable degree by both basin types. However, the pool of water characteristic of a retention basin offered a superior environment for the removal of soluble pollutant forms, particularly nitrogen and phosphorus.
The treatment obtainable in detention and retention basins make them effective devices for the abatement of urban runoff pollution. Through the mechanisms of solids settling and microbial degradation, a basin can treat polluted runoff to a considerable extent and reduce damage to receiving bodies of water. / M.S.
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