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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Modeling Historical Meander Bends Reconnection on the lower Long Tom River in Lane Co. and Benton Co., OR

Appleby, Christina 21 November 2016 (has links)
Since the damming and channelization of the lower Long Tom River in the 1940s and 1950s, the quality and quantity of habitat for coastal cutthroat trout and spring Chinook salmon in the watershed has dramatically diminished. In order to better understand the potential for stream restoration, this study uses 2D hydraulic modeling to determine the impact of reconnecting historical meander bends to the main stem of the lower Long Tom River on localized flooding, sediment erosion and deposition, and salmonid physical habitat. These models compare the current conditions to two restoration scenarios that allow for fish passage given 1, 2, and 5-year flood events at two study sites. This study reveals important variations in the impact of restoration between the study sites and the reconnection methods. It also suggests that there is the potential for a large increase in the area of accessible habitat with stream restoration.
12

Ice, wood and rocks : regulating elements in riverine ecosystems

Engström, Johanna January 2010 (has links)
Riparian ecosystems are of great importance in the landscape, connecting landscape elements longitudinally and laterally and often encompassing sharp environmental gradients in ecological processes and communities. They are influenced by fluvial disturbances such as flooding, erosion and sediment deposition, which create dynamic and spatially heterogeneous habitats that support a high diversity of species. Riverine ecosystems belong among the world’s most threatened systems. In rivers throughout the world, human alterations to fluvial disturbance regimes have resulted in degraded ecosystems and species loss. For example, in Sweden, watercourses of all sizes have been channelized to facilitate timber floating, but in the last 10–20 years the impacts in some of the affected rivers have been reduced by restoration actions. The objectives of this thesis are to evaluate how riverine ecosystems in general, with specific focus on riparian communities, are affected by (1) restoration of channelized reaches by boulder replacement, (2) ice formation, and (3) restoration of in-stream wood abundance in the stream channel. Objective (1) was assessed by quantifying the retention of plant propagules in channelized and restored stream reaches and by evaluating effects on riparian plant and bryophyte communities in disconnected and re-opened side channels. Retention of plant propagule mimics was highest at low flows and in sites where boulders and large wood had been replaced into the channel. Propagules are however unlikely to establish unless they can be further dispersed during subsequent spring high flows to higher riparian elevations suitable for establishment. Thus, immigration to new suitable sites may occur stepwise. Our study demonstrates that restoration of channel complexity through replacement of boulders and wood can enhance retention of plant propagules, but also highlights the importance of understanding how restoration effects vary with flow. We detected no differences in riparian diversity between re-opened and disconnected side channels, but we did observe significant differences in species composition of both vascular plant and bryophyte communities. Disconnected sites had more floodplain species, whereas restored sites had more species characteristic of upland forest. This suggests that the reopening of side channels resulted in increased water levels, resulting in new riparian zones developing in former upland areas, but that the characteristic floodplain communities have not had time to develop in response to the restored fluvial regime. Objective (2) was approached by evaluating the effect of both natural anchor ice formation and experimentally created ice in the riparian zone. Riparian plant species richness and evenness proved to be higher in plots affected by anchor ice. Plants with their over-wintering organs above the ice sheet suffered from the treatment but the overall species richness increased in ice-treated plots. Objective (3) was evaluated by studying wood recruitment and movement, channel hydraulics, propagule retention and fish abundance in streams restored with large wood. Only one stream experienced reduced velocities after large wood addition. The large size and reduced velocity were probably also the reasons why this stream proved to be the best one in trapping natural, drifting wood. Increased retention and decreased mechanical fragmentation in large wood sites will lead to decreased loss of detritus from the site and therefore higher availability of coarse particulate organic matter which can result in more species rich shredder communities. Our study did not show that the occurrence of large wood had an important role in controlling density or biomass of brown trout.
13

Spatial Optimisation for River Restoration Planning in Nova Scotia, Canada

Oldford, Greig 23 August 2013 (has links)
River restoration is believed to have the greatest chance of success when action is considered in the broader context of the riverscape. However, methods are lacking to fully integrate systemic connectivity into decision-making. Optimisation, a method of prioritisation, is capable of accounting for longitudinal connectivity, spatial interdependence, and cumulative effects of anthropogenic barriers such as dams and culverts. In addition, optimisation can help ensure that limited restoration funds are efficiently allocated. Despite these advantages, it remains under-employed. I present optimisation models for maximising connectivity within a river network (i.e., undirected connectivity) and connectivity between the network and its outflow (i.e., directed connectivity) and demonstrate their application on three river networks in Nova Scotia, Canada. Non-additive cumulative effects of barriers and key budget thresholds that yielded better returns on investment were observed. The methods and models address current challenges in implementation of the optimisation approach to systematic river restoration planning. / Master's Thesis
14

USING 1D2D MODELING TO INFORM RESTORATION EFFORTS IN THE ATCHAFALAYA RIVER BASIN, LOUISIANA

Hayden-Lesmeister, Anne 01 August 2018 (has links)
The Atchafalaya River Basin (ARB) in Louisiana is the principal distributary of the Mississippi River, and it contains the largest contiguous area of baldcypress-water tupelo swamp forests in North America. After designation of the ARB as a federal floodway following the destructive 1927 Mississippi River (MR) flood, it was extensively modified to accommodate a substantial portion of the MR flow (~30%) to mitigate flooding in southern Louisiana. The resulting reach to system scale modifications for regional flood mitigation, navigation, and hydrocarbon extraction have substantially altered the lateral connectivity between the AR and its floodplain wetlands, threatening the ecological integrity of this globally-important ecosystem. Multiple stakeholder groups agree that restoring flow connectivity is essential to maintaining the basin’s water quality and forest health, and several flow-connectivity enhancement projects (hereafter, project elements) have been proposed by the Atchafalaya Basin Program’s Technical Advisory Group within the Flat Lake Water Management Unit (FLWMU) study area to increase lateral hydrologic connectivity within the management unit and beyond. Additionally, a new flow prescription to improve floodplain habitat has recently been suggested for the ARB. Flow into the ARB is now regulated through the Old River Control Structure (ORCS; operational in 1963), and represents the opportunity for large-scale flow experiments to enhance a multitude of ecosystem services that have been degraded due to anthropogenic alteration. For this study, I compiled existing datasets and constructed a 1D2D hydraulic model to evaluate: 1) if the suggested flow prescription would have the desired inundation impacts; 2) whether the proposed project elements would improve lateral connectivity in the FLWMU; and 3) whether recommended project elements would increase the area suitable for baldcypress recruitment in the study area. To examine the first two research questions above, I examined two scenarios – a baseline scenario to examine current conditions (no restoration projects), and a full-implementation scenario, where all proposed project elements that could be examined at the model resolution were implemented. Comparison of the modeling results for the baseline scenario to the suggested flow prescription goals suggests the overbank discharge and the extreme low-flow targets would have the desired impacts of inundating and drying out of the majority of the FLWMU, respectively. Proxy indicators of enhanced flow connectivity suggest that proposed projects will improve water quality, especially at intermediate to high flow conditions, when ~90% of the FLWMU experiences improved drainage as indicated by higher rates of water surface elevation decrease and lower overall system water volume. The stated objectives of the project elements recommended by the Technical Advisory Group are to improve connectivity and water quality, but another important and related restoration goal for stakeholders includes baldcypress restoration. To examine the third objective, I used a model-derived proxy indicator of habitat improvement (depth reduction) at two key discharges, along with other ecological suitability factors, to determine areas most likely to support baldcypress recruitment. Here, I compared baseline conditions to two alternative restoration scenarios – 1) a targeted implementation scenario where 22 project elements were implemented, and 2) the full-implementation scenario, where all projects that could be examined at the model resolution were implemented. Suitable habitat area for both natural and artificial baldcypress recruitment increased under intermediate flow conditions but remained unchanged for higher discharge conditions. For the intermediate discharge scenario, the full-implementation scenario results in a 2 km2 increase in the class considered most suitable for natural baldcypress regeneration within the calculated recruitment band, and a decrease of ~16 km2 in the areas considered least suitable for the entire FLWMU study area. Coupled with the connectivity results, which indicate that nutrient-rich river water will be exchanged between main channels and the backswamp at a greater range of flows, it appears that project implementation alone will benefit baldcypress recruitment, especially artificial regeneration efforts. However, full project implementation coupled with large-scale flow modifications at ORCS would likely provide maximum benefit for baldcypress restoration efforts that seek to increase the area supportive of natural baldcypress regeneration.
15

Assessment of Methods for Monitoring Responses to River Restoration: Riverbed and Channel Form Changes

Tu, Denise Shao-Wai 06 1900 (has links)
xi, 54 p. : ill. (some col.) / On the Middle Fork John Day River (MFJD), a low gradient, meandering river in eastern Oregon, restoration includes engineered log structures intended to increase in-stream complexity and habitat diversity. Effects of log structures on riverbed topography can be captured through repeat topographic surveys, digital elevation model (DEM) of differencing (DoD), and aerial imagery. This study evaluates the (1) potential for remote sensing analysis, (2) effect of survey point density on DEMs, and (3) application of DoDs, in monitoring riverbed changes in the MFJD. An average point spacing and density finer than 0.50m and 1.25pts/m<super>2</super> captures riverbed complexities. Although elevation changes were expected to be minimal, DoDs revealed -0.9 to 0.5m elevation changes associated with log structure designs. Incorporating numerical thresholds into future monitoring survey methods will improve the modeling of MFJD riverbed surfaces. Monitoring riverbed changes through DoDs can inform improvements to future restoration design and the effectiveness of log structures. / Committee in charge: Patricia McDowell, Chairperson; Andrew Marcus, Member
16

Leadership Dynamics in Collaboration: Lessons from the Middle Fork John Day River Intensively Monitored Watershed Collaboration

Dutterer, Andrew 27 October 2016 (has links)
This study explores leadership dynamics in collaborative governance. The research features a collaboration case study of sixteen federal and state agency and NGO stakeholders. The collaboration is conducting a ten-year, basin-scale monitoring project of salmonid habitat restoration projects in the Middle Fork John Day (MFJD) River basin in Eastern Oregon. The monitoring project is known as an intensively monitored watershed (IMW), one of sixteen throughout the Pacific Northwest. The research is guided by the following question: How do leadership dynamics in the MFJD IMW collaborative governance structure facilitate effective collaborative process or create limitations to that process? This study uses qualitative research methods in evaluating multiple research sources. Insights from this study may prove valuable in providing guidance on effectively structuring and managing basin-scale collaborative habitat monitoring projects, including future IMW projects. This study further aims to contribute to research on collaborative leadership for the greater scholarship on collaboration.
17

Ecological and social dimensions of restoration success in boreal river systems

Marttila, M. (Maare) 28 November 2017 (has links)
Abstract The degradation of rivers and streams has led to world-wide efforts to restore freshwater habitats. A good understanding of the social-ecological context is considered key to successful restoration. In this thesis, a multidisciplinary framework was applied to study ecological and social dimensions of restoration success. First, the long-term performance of in-stream restoration measures was examined by conducting repeated cross-sectional surveys in restored streams up to 20 years post-restoration. Next, nationwide electrofishing data were used to assess the density responses of juvenile salmonids to habitat restoration and factors influencing restoration success were examined. Finally, changes in the provision of ecosystem services were evaluated by comparing the perceptions of restoration outcomes between two user groups and three study rivers. The results indicated that the restoration-induced increase in habitat heterogeneity persisted over time, initiating an overall positive development also in biological metrics (i.e. juvenile salmonids and aquatic mosses). However, overall substrate variability in restored streams remained lower than in near-pristine streams, with a shortage of gravel beds. Fish responses varied strongly between rivers, which was explained mainly by watershed scale (e.g. river basin size, dominant geology) and local (potential interspecific competition) factors. Site-specific differences were also observed in the delivery of ecosystem services, mainly reflecting stakeholder perceptions of landscape value and fish provisioning. Overall, the results show that setting indicators and target levels for restoration success is grounded on perspective. Socially conscious ecological restoration that acknowledges local specialities and needs in priority setting, planning and implementation has the potential to provide multiple benefits for river ecosystems and society. / Tiivistelmä Virtavesien ekologisen tilan heikentyminen on johtanut maailmanlaajuisiin toimiin niiden elinympäristöjen kunnostamiseksi. Usein ekologisen kunnostuksen onnistuminen edellyttää kuitenkin ihmisen ja ympäristön vuorovaikutussuhteiden laaja-alaista ymmärtämistä. Tässä väitöskirjatutkimuksessa käytettiin monitieteistä viitekehystä virtavesikunnostusten ekologisten ja sosiaalisten vaikutusten tutkimiseen. Ensimmäisessä osatyössä arvioitiin kunnostustoimenpiteiden kestävyyttä sekä uoman rakenteellisen monimuotoisuuden kehittymistä pitkällä aikavälillä (10-20 vuotta kunnostusten jälkeen). Toisessa osatyössä tehtiin valtakunnallisen sähkökalastusaineiston avulla meta-analyysipohjainen yhteenveto suomalaisten virtavesikunnostusten vaikutuksista taimenen ja lohen kesänvanhojen (0+) poikasten tiheyteen sekä tutkittiin kunnostustulokseen vaikuttavia ympäristötekijöitä. Kolmannessa osatyössä selvitettiin kunnostusten onnistumista ekosysteemipalvelujen näkökulmasta vertaamalla kahden eri käyttäjäryhmän kokemia muutoksia kolmen tutkimusjoen välillä. Väitöskirjan tulokset osoittivat, että kunnostukset lisäsivät jokiuoman rakenteellista monimuotoisuutta sekä lyhyellä että pitkällä aikavälillä ja vaikuttivat myönteisesti myös biologisiin indikaattoreihin (lohikalojen poikastiheys ja vesisammalet). Vaihtelu pohjan laadussa oli kuitenkin luonnontilaisia uomia vähäisempää ja erityisesti kutuun soveltuvaa soraa oli niukasti. Lohikalojen tiheysvaste vaihteli voimakkaasti jokien välillä, mikä selittyi pääasiassa valuma-alueeseen liittyvillä (esim. valuma-alueen koko ja geologia) ja paikallisilla (mahdollinen lajien välinen kilpailu) tekijöillä. Paikkasidonnaisia eroja havaittiin myös vaikutuksissa ekosysteemipalveluihin ja ne heijastivat etenkin maisemassa ja kalasaaliissa koettuja muutoksia. Tutkimus osoitti, että erilaiset taustat ja odotukset vaikuttavat vahvasti siihen, millaisten kriteerien perusteella kunnostusten onnistumista arvioidaan. Jotta kunnostuksilla saavutettaisiin hyötyjä sekä jokiekosysteemeille että yhteiskunnalle, on tärkeää tuntea paikalliset erityispiirteet ja -tarpeet ja ottaa ne huomioon kunnostuskohteiden valinnassa sekä toimenpiteiden suunnittelussa ja toteutuksessa.
18

Holásecká jezera / Lakes of Holasky

Šubrt, Jiří January 2014 (has links)
Master´s thesis deals with the study of lakes locality called Holasecka jezera in southern part of Brno. The study gives complex evaluation of present condition of the locality and closely aims at Holasecka jezera restoration, including technical and environmentally friendly measures. Restoration and construction of new water management objects is designed together with creation of nature development zones and financial evaluation of designed measures.
19

Evaluation of Stream Bank Restoration to Improve Water Quality in a Semi-Arid Stream

Neenan, Johnathan 01 December 2019 (has links)
Human watershed activities such as converting land cover to agriculture and livestock grazing have negatively impacted stream water quality worldwide. One such case is Utah’s Upper Sevier River where a loss of woody bank vegetation (reduced shading) and accelerated bank erosion (increased fine sediment inputs) has led to increased stream temperature and water turbidity. As a result, the state of Utah sought to improve water quality conditions using streambank restoration. While commonly recommended and performed, the effectiveness of this sort of restoration has rarely been quantified. Here, I evaluated a restored reach of the Upper Sevier River near Hatch, UT using continuous monitoring data and a historical photo analysis. As Utah wishes to continue performing this type of restoration in additional locations on the Upper Sevier River, I applied a simple sediment budget model to test its value in informing future streambank restoration decisions. Continuous monitoring data at the upstream and downstream extent of restoration showed that both stream temperature and turbidity increased downstream along the restored reach. In addition, I found that stream temperature violated Utah’s cold-water stream threshold at both sites but did not violate thresholds for rainbow trout. Turbidity violated state and biological thresholds at both sites. I was unable to conclude whether the streambank restoration directly altered water quality because I lacked monitoring data before restoration occurred. Results of the historical aerial photo analysis showed that restoration practitioners were successful in reducing cut bank erosion. My use of SIAM as a simple sediment budget model proved insufficient due to poor data quality and quantity. Overall, streambank restoration was successful at reducing cut bank erosion, and I recommended monitoring future restoration before and after project completion, identifying and monitoring upstream sources of fine sediment, and pursuing more comprehensive sediment models to inform future streambank restoration.
20

Mithi River Restoration Project / Mithi River Revitalisation Project

Sanghani, Himanshu January 2009 (has links)
It took only few years to turn a naturally owing river into a drain. 17.84 k.m stretch of MithiNadi (river), an arterial river, running along north-south axis of Bombay (Mumbai) is facing the grimproblems of backyard atrocities. Finding its way through the odds of household garbage, industrialsewage, other pollutants and encroachments, Mithi river originates from the conuence of two essentialreservoirs; Vihar Lake and Powai Lake and merging with Arabian Sea at Mahim creek. The stategovernment is trying to rescue the river with their elusive plan but is being implemented with lessconcurrency in mind. The responsibility of restoring the river being shared between two authoritiesMumbai Metropolitan Region Development Authority (MMRDA) and BrihanMumbai MunicipalCorporation (BMC) directed by Mithi River Development and Planning Authority (MRDPA), givesa deceptive impression of revival and truth. Currently the authorities are resettling the informals,widening and deepening the river simultaneously building the retaining wall to safeguard the bank.The odds would be if both the authorities shell up a unique comprehensive plan under MRDPA forrestoring the river involving community. The aim of this report is to devise a 'design based' restorationplan to achieve long term riparian ecosystem and sustainability of Mithi river. The restoration strategiesfor urban rivers are understood by analysing the riparian ecosystem techniques through literaturereading on river -engineering, river -morphology and reviewing Los Angeles River, California-USA andCheonggyecheon River in Korea cases. Dealing with odds Mithi Nadi (river) is facing today and basedon socio-economic background and technical design aspects for the river, this master thesis proposes a3-Phase restoration model method to achieve the target. Phase-I would involve community awarenesswith participatory approach while building strong network, it also highlights a plan in segmenting theriver into 10 divisions for Phase-II surveillance and incognisant waste disposal methods. Phase-II of applyingriparian techniques will then be initiated bearing the narrow widths, existing residential sectorsalong the bank and current urbanization. Finally, Phase-III will commence with a community basedmonitoring plan underpinning Phase-I sectoral division plan for the river. The proposal is discussedusing SWOT analysis and whether the implications of the techniques are suitable in retrospective. Butnally it can be said that although there are several ways to restore a river, best strategy can only beachieved through community participation by fractioning their inputs appropriately.

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