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Terrestrial Laser Scanning for Quantifying Uncertainty in Fluvial ApplicationsResop, Jonathan P. 20 July 2010 (has links)
Stream morphology is an important aspect of many hydrological and ecological applications such as stream restoration design (SRD) and estimating sediment loads for total maximum daily load (TMDL) development. Surveying of stream morphology traditionally involves point measurement tools, such as total stations, or remote sensing technologies, such as aerial laser scanning (ALS), which have limitations in spatial resolution. Terrestrial laser scanning (TLS) can potentially offer improvements over other surveying methods by providing greater resolution and accuracy. The first two objectives were to quantify the measurement and interpolation errors from total station surveying using TLS as a reference dataset for two fluvial applications: 1) measuring streambank retreat (SBR) for sediment load calculations; and 2) measuring topography for habitat complexity quantification. The third objective was to apply knowledge uncertainties and stochastic variability to the application of SRD.
A streambank on Stroubles Creek in Blacksburg, VA was surveyed six times over two years to measure SBR. Both total station surveying and erosion pins overestimated total volumetric retreat compared to TLS by 32% and 17%, respectively. The error in SBR using traditional methods would be significant when extrapolating to reach-scale estimates of sediment load. TLS allowed for collecting topographic data over the entire streambank surface and provides small-scale measurements on the spatial variability of SBR.
The topography of a reach on the Staunton River in Shenandoah National Park, VA was measured to quantify habitat complexity. Total station surveying underestimated the volume of in-stream rocks by 55% compared to TLS. An algorithm was developed for delineating in-stream rocks from the TLS dataset. Complexity metrics, such as percent in-stream rock cover and cross-sectional heterogeneity, were derived and compared between both methods. TLS quantified habitat complexity in an automated, unbiased manner at a high spatial resolution.
Finally, a two-phase uncertainty analysis was performed with Monte Carlo Simulation (MCS) on a two-stage channel SRD for Stroubles Creek. Both knowledge errors (Manning's <i>n</i> and Shield's number) and natural stochasticity (bankfull discharge and grain size) were incorporated into the analysis. The uncertainty design solutions for possible channel dimensions varied over a range of one to four times the magnitude of the deterministic solution. The uncertainty inherent in SRD should be quantified and used to provide a range of design options and to quantify the level of risk in selected design outcomes. / Ph. D.
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Surface Water and Groundwater Hydraulics, Exchange, and Transport During Simulated Overbank Floods Along a Third-Order Stream in Southwest VirginiaGuth, Christopher Ryan 20 June 2014 (has links)
Restoring hydrologic connectivity between the channel and floodplain is a common practice in stream and river restoration. Floodplain hydrology and hydrogeology impact biogeochemical processing and potential nutrient removal, yet rigorous field evaluations of surface and groundwater flows during overbank floods are rare. We conducted five sets of experimental floods to mimic floodplain reconnection. Experimental floods entailed pumping stream water onto an existing floodplain swale, and were conducted throughout the year to capture seasonal variation. Each set of experimental floods entailed two replicate floods occurring on successive days to test the effect of varying antecedent moisture. Water levels and specific conductivity were measured in surface water, shallow soils, and deep soils, along with surface flow into and out of the floodplain. Total flood water storage increased as vegetation density increased and or antecedent moisture decreased. Hydrologic flow mechanisms were spatially and temporally heterogeneous in surface water, in groundwater, as well as in exchange between the two and appeared to coexist in small areas. Immediate propagation of hydrostatic pressure into deep soils was suggested at some locations. Preferential groundwater flow was suggested in locations where the pressure and electrical conductivity signals propagated too fast for bulk Darcy flow through porous media. Preferential flow was particularly obvious where the pressure signal bypassed an intermediate depth but was observed at a deeper depth. Bulk Darcy flow in combination with preferential flow was suggested at locations where the flood pressure and electrical conductivity signal propagated more slowly yet arrived too quickly to be described using Darcy's Law. Finally, other areas exhibited no transmission of pressure or conductivity signals, indicating a complete lack of groundwater flow. Antecedent moisture affected the flood pulse arrival time and in some cases vertical connectivity with deeper sediments while vegetation density altered surface water storage volume. Understanding the variety of exchange mechanisms and their spatial variability will help understand the observed variability of floodplain impacts on water quality, and ultimately improve the effectiveness of floodplain restoration in reducing excess nutrient in river basins. / Master of Science
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Complementary Effects of In-Stream Structures and Inset Floodplains on Solute RetentionAzinheira, David Lee 14 June 2013 (has links)
The pollution of streams and rivers is a growing concern, and environmental guidance increasingly suggests stream restoration to improve water quality. �Solute retention in off channel storage zones such as hyporheic zones and floodplains is typically necessary for significant reaction to occur. �Yet the effects of two common restoration techniques, in stream structures and inset floodplains, on solute retention have not been rigorously compared. �We used MIKE SHE to model hydraulics and solute transport in the channel, inset floodplain, and hyporheic zone of a 2nd order stream. �We varied hydraulic conditions (winter baseflow, summer baseflow, and storm flow), geology (hydraulic conductivity), and stream restoration design parameters (inset floodplain length, and presence of in stream structures). �In stream structures induced hyporheic exchange during summer baseflow with a low groundwater table (~20% of the year), while floodplains only retained solutes during storm flow conditions (~1% of the year). �Flow through the hyporheic zone increased linearly with hydraulic conductivity, while residence times decreased linearly. �Flow through inset floodplains and residence times in both the channel and floodplains increased non linearly with the fraction of bank with floodplains installed. �The fraction of stream flow that entered inset floodplains was one to three orders of magnitude higher than that through the hyporheic zone, while the residence time and mass storage in the hyporheic zone was one to five orders of magnitude larger than that in floodplain segments. �Our model results suggest that in stream structures and inset floodplains are complementary practices. / Master of Science
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Improving Design Guidance for In-Stream Structures Used in Stream RestorationHickman, Elizabeth L. 25 March 2019 (has links)
Vane-type in-stream structures and step pool storm conveyance (SPSC) are more ecologically friendly alternatives to traditional stream channel stabilization and stormwater conveyance techniques. Vane-type structures have been widely accepted as elements of stream restoration projects and are regularly implemented in streams throughout the United States. However, these structures commonly experience partial or total failures of function or stability, often due either to improper installation or misapplication. This study undertook a thorough review of the available design guidance for the single-arm vane, j-hook vane, cross vane, and w-weir, which revealed that the existing guidance is composed of non-standardized recommendations largely based on practitioner experience and rules of thumb. Existing guidance was synthesized with current structure research and practitioner surveys to create factsheets for each of the four structures and the SPSC, with the intent of improving structure application and offering concise general guidance. This study also endeavored to improve the design of the SPSC by determining the most accurate of several common prediction methods for Manning's roughness coefficient n, used in SPSC design velocity calculations. This was done by using Rhodamine WT dye tracer experiments to determine n values during storm flows in two SPSC structures in Annapolis, MD, which were then compared to predicted n values. Values of Manning's n determined in the SPSCs at low flows (0.28-12) often exceeded the predicted n values (-0.17-3.9) by several orders of magnitude. Though the applicability of these results is limited, an increase in design n to 0.1-0.2 is still recommended. / Master of Science / Vane-type in-stream structures are stone or wood structures installed within a stream channel for purposes such as streambank stabilization or aquatic habitat creation. Step pool storm conveyance (SPSC) is a technique which converts an existing steep stream or gully into a step-pool channel. Both of these techniques are more ecologically friendly than many traditional stream channel stabilization or stormwater conveyance techniques such as riprap or concrete storm drains. Vane-type structures in particular have been widely accepted as elements of stream restoration projects and are regularly implemented in streams throughout the United States. However, these structures commonly experience partial or total failures, either through structural collapse or failure to function properly. This is often either because they were improperly installed or because they were installed at a stream site where they were inappropriate or unnecessary. A review of the available guidance for the design of these structures revealed that the existing guidance is composed of non-standardized and sometimes contradictory recommendations which are largely based on designer trial and error and rules of thumb, rather than on the results of scientific experiments or modeling. The goal of this study was to improve the success of vane-type in-stream structures and the SPSC by providing factsheets offering clear and concise general design guidelines and sound recommendations for structure application. Flow studies of two SPSC structures in Annapolis, MD were also conducted to improve the design of that structure by measuring its flow characteristics in the field.
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Kan förändringar i bottenfaunan påvisas två år efter en bäckrestaurering? / Can changes in the benthos be detected two years after a steam restoration?Averhed, Björn January 2010 (has links)
<p>The aim of this work is to analyze if a change in the benthic community can be detected two years after a restoration of a small stream. The samples were taken in a small stream at Tinnerö Eklandskap just south of Linköping. In addition to the restored area, two reference sites upstream and downstream of the restored area were sampled to compare to the restored site. The method used for sampling of benthic fauna in the stream was kick sampling. ASPT, Berger-Parker and Renkonen-indices were used to find out if there was any difference between the reference areas and the restored area. In addition to indices, rank-abundance curves and species lists were made to see if there was any trend difference between the different areas. The only index that showed a difference between the different areas was Berger-Parker diversity index. The reason why there were no greater differences between the areas may be due to the fact that two years is too short to allow time for the benthos to re-colonize the restored area.</p>
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Kan förändringar i bottenfaunan påvisas två år efter en bäckrestaurering? / Can changes in the benthos be detected two years after a steam restoration?Averhed, Björn January 2010 (has links)
The aim of this work is to analyze if a change in the benthic community can be detected two years after a restoration of a small stream. The samples were taken in a small stream at Tinnerö Eklandskap just south of Linköping. In addition to the restored area, two reference sites upstream and downstream of the restored area were sampled to compare to the restored site. The method used for sampling of benthic fauna in the stream was kick sampling. ASPT, Berger-Parker and Renkonen-indices were used to find out if there was any difference between the reference areas and the restored area. In addition to indices, rank-abundance curves and species lists were made to see if there was any trend difference between the different areas. The only index that showed a difference between the different areas was Berger-Parker diversity index. The reason why there were no greater differences between the areas may be due to the fact that two years is too short to allow time for the benthos to re-colonize the restored area.
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A prototype decision support system for streambank rehabilitation.Schoeman, Kilaan Christopher. January 2001 (has links)
The condition of a stream is often judged by the state of its banks. This, the lack of adequate
advice for streambank rehabilitation, and the drive by legislation, particularly the National Water
Act, 1998 (RSA Act no. 36 of 1998) and the National Environmental Management Act, 1998
(RSA Act no. 107 of 1998), to restore South African riparian areas, created a need for more
information into such systems. Identifying a gap in what we know about rehabilitating degraded
streambanks led to the development of a decision support system for the selection of
streambank rehabilitation techniques. The Streambank Rehabilitation Decision Support System,
or SR-DSS, aims to provide riparian managers with advice on choice of technique at degraded
streambank locations along a river system. Techniques were sought from the scientific literature
and organised to recommend appropriate techniques for combating certain erosive processes.
Rutherford et al. (1999) conclude that placing priority on sites of lower importance may be an
inefficient manner of spending the resources at hand. Foreseeing this likelihood, a priority setting
system was developed and based on the principles of Rutherfurd et al. (1999). These principles
aim to prioritise human interests without compromising ecological interests. Along a given
stream, the areas of degradation that compromise property will nearly always have the highest
priority. Once these have been addressed, sites of ecological value are taken into consideration
followed by sites that require substantial effort to restore. It is argued that sites taking substantial
effort to restore have the least to 'loose' should they degrade further.
To enable the use of these principles a site scoring system was developed, so that sites could
be prioritised. This was based on the value and threat rating tables developed by Heron et al.
(1999). It was soon realised that a framework was needed within which the above could be set.
For this purpose, Kapitzke's (1999) planning and design procedure was adapted to form an
eleven-step framework which would guide the rehabilitation venture from priority setting, to the
treatment outcome. The rehabilitation approach was tested in the case of the Foxhill Spruit. The
small size of the catchment allowed the different segments of the approach (framework, priority
setting model, field assessment sheet and SR-DSS) to be tested in real world conditions. The
approach was found to have a number of strengths. The framework brought to the attention of
the user, the dominant forces at play at each site, and was useful in determining the
recommendation given by SR-DSS. The priority setting model allowed sites to be arranged in
order of priority, that, according to Rutherfurd et al. (1999), would be the most efficient in terms
of ecological value maintained, and resources saved. The field assessment sheet was
consistent in rating the degree of intervention required, and in each case directed the user to the
appropriate sections in SR-DSS. SR-DSS recommended appropriate techniques that would
match the erosive forces occurring at each site. Comparing the technique chosen by SR-DSS
to techniques that may have been recommended instead substantiated this finding. The
techniques chosen by SR-DSS were found to be superior. This approach considers all aspects
of sound streambank rehabilitation and may be used to gain advice on small streams in South
Africa. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.
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Water quality factors affecting the restoration of the Rio GrandePeinado Coronado, Porfirio, January 2007 (has links)
Thesis (M.S.)--University of Texas at El Paso, 2007. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.
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The application of a two-dimensional sediment transport model in a Cumberland Plateau mountainous stream reach with complex morphology and coarse substrateJohnson, Daniel Hale. January 2008 (has links) (PDF)
Thesis (M.S.)--University of Tennessee, Knoxville, 2008. / Title from title page screen (viewed on Sept. 23, 2009). Thesis advisor: John S. Schwartz. Vita. Includes bibliographical references.
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DEVELOPMENT OF TECHNIQUES FOR ASSESSING AND RESTORING STREAMS ON SURFACE MINED LANDSBlackburn-Lynch, Whitney Cole 01 January 2015 (has links)
Surface mining is a commonly used method for extracting coal in the Appalachian Coalfields of the U.S. This mining practice produces excess spoil or overburden, which is often placed in adjacent valleys resulting in the creation of valley fills. These valley fills bury headwater streams, which in turn can negatively impact downstream ecosystems. In 2008, the University of Kentucky designed and constructed 1,020 m of ephemeral, intermittent and headwater streams on an existing valley fill (Guy Cove) as a proof-of-concept. The goal of the project was to evaluate whether or not a stream recreation could occur on mined lands, particularly a valley fill. The hydrograph characteristics discharge volume, peak discharge, discharge duration, peak time, lag time, and response time were evaluated from three watersheds: (1) unmined, forested watershed (control), (2) partially restored watershed with the intermittent stream (Guy Cove), and (3) a mined watershed with an unrestored stream (valley fill with traditional mined land reclamation practices). Results from four years of monitoring indicate that the created intermittent stream at Guy Cove is hydrologically similar to the control during storm events; however, differences were noted for base flow. A new stream restoration design technique, which combines natural channel design and furrow irrigation design protocols, was investigated.
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