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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.
341

Multi-scale hydrological information system using an OGC standards-based architecture

Dong, Jingqi 08 July 2011 (has links)
A Multi-Scale Hydrological Information System (HIS) includes three levels of HIS, which are the national CUAHSI HIS, the Texas HIS and the local Capital Area Council of Governments (CAPCOG) HIS. The CUAHSI Hydrologic Information System has succeeded in putting water data together using a Services-Oriented Architecture (SOA). However, maintaining the current metadata catalog service has been problematic. An Open Geospatial Consortium (OGC) standard transformation procedure is happening to transfer the current web services into OGC adopted services and models. The transformation makes CUAHSI HIS compliant with the international OGC standards and to have the capability to host tremendous water data. On a scaled down level, the Texas HIS has been built for the specific Texas hydrologic data, concerning the variables and the web services listed in this thesis. The CAPCOG emergency response system was initiated for the purpose of the Texas flash flood warning, including several data services, such as the USGS NWIS, the City of Austin (COA) and the Lower Colorado River Authority (LCRA). By applying the consistent mechanism, which is the OGC standards-based SOA, in these three scales of HIS, three catalogs of services can be created within the architecture, and hydrologic data services included in different catalogs can be searched across. Each catalog of services has a different scale or purpose. A technique, called KiWIS developed by the KISTERS Company, of publishing OGC standard web services through the WISKI hydrologic database was then described. The technique has been applied to the City of Austin’s water data hosted at CRWR. The OGC standard transformation progress reviewed in the thesis and the technique described can give a reference on how to synthesize Multi-Scale HIS within a standard mechanism. / text
342

The Impact of El Niño Southern Oscillation Events on Water Resource Availability in Central Sulawesi, Indonesia. / A hydrological modelling approach / Einfluss von ENSO Ereignissen auf die Wasserressourcen im Palu River Einzugsgebiet, Zentral-Sulawesi, Indonesien. / Ein hydrologischer Modellierungsansatz

Leemhuis, Constanze 28 October 2005 (has links)
No description available.
343

Sausintų pelkių būklės įvertinimas ir renovacijos pasiūlymai / The Estimation Of Drained Swamps State And Suggestion Of Renovation

Barakauskas, Justas 14 January 2009 (has links)
Darbe nagrinėjama nusausintų pelkių degradavimas, jų hidrologinio rėžimo būklė, jo atstatymo galimybės ir pasiūlymai. Analizuojami ir įvertinami pelkių renovacijos būdai. Pelkių tyrimams buvo panaudota specializuota šiems darbams technika ir įprasta mokslinių tyrimų metodika. Geologiniams tyrimams naudotasi pelkių zondu, hidrologiniams – plonasieniai skydai, aukščių ir vietų nustatymui – nivelyras ir GPS įranga. Atlikus tyrimus ir išanalizavus gautus duomenis, buvo atliktas rezultatų įvertinimas. Didžiausią įtaką aukštapelkių būklei turi sausinimo poveikis. Visų trijų nagrinėjamų pelkių hidrologinis rėžimas yra pažeistas, degraduoja aukštapelkinė ekosistema, nyksta durpių klodai, kyla gaisrai, gresia pelkinės bioįvairovės rūšių išnykimas. Hidrologinio rėžimo atkūrimas būtų geriausia priemonė sustabdyti pelkių degradavimą. Todėl būtina sustabdyti pelkių sausinimą. Grioviuose įrengti užtvankas, kurios sudarytų sąlygas pakelti vandens lygį aukštapelkėse. / The study researches into the degradation of drained bogs, the status of their hydrological regime, possibilities and proposals concerning its restoration. The methods of bog renovation are analysed and evaluated. In the bog research, specialized technical means of this area and the usual scientific research methodology were employed. The following equipment was used: bog probe in geological research, thin-walled screens in hydrological research, levelling instrument and GPS equipment for the determination of altitudes and location. After research and analysis of the data obtained, the evaluation of results was carried out. The effect of draining has the biggest impact on upland bogs. The hydrological regime of all three bogs considered in the study is affected negatively, the upland bog ecosystem is under degradation, peat layers are diminishing, fires emerge, there is a threat of extinction of various species making up the bog biological diversity. The restoration of the hydrological regime would be the best measure to stop bog degradation. Therefore, bog drainage has to be stopped. Dikes should be constructed in trenches in order to form conditions to lift the water level in upland bogs.
344

Hydrologic modeling of an agricultural watershed in Quebec using AGNPS

Perrone, Jim T. January 1997 (has links)
A research study was undertaken to determine the predictive capability of the AGNPS model with respect to surface runoff, peak flow, and sediment yield produced by rainfall-runoff events on a 26 km$ sp2$ watershed in Quebec. Precipitation, stream discharge, surface runoff, and suspended sediment concentrations were monitored for rainfall-runoff events occurring from 1994-96, inclusive. Data describing stream patterns, topography, soil type, and land use were collected and input to the model. / Seven rainfall-runoff events were used for model calibration. Five storms were used to validate the model. Calibration curves were developed to correlate the antecedent precipitation index (API) to the SCS curve number. For model calibration, coefficients of performance of 0.05, 0.43, and 0.12 were obtained for surface runoff, sediment yield, and peak flow, respectively. For model validation, coefficients of performance (CP$ rm sp prime sb{A}$) of 0.02, and 0.01 were obtained for surface runoff, and sediment yield, respectively. Peak flow was generally overpredicted and yielded a CP$ rm sp prime sb{A}$ of 2.07. / A sensitivity analysis showed API and associated curve numbers to be the most sensitive input parameters. USLE factors were also sensitive. The surface condition parameter and Manning's n had negligible influence on model output. The hydrograph shape factor toggle parameter showed extreme sensitivity. / A simulation of best management practices on the basin estimated soil loss reductions of 15 to 25% for storms of varying magnitudes if a 4-year crop rotation implementing conservation tillage were to be adopted.
345

Hydrological Modeling for Climate Change Impact Assessment : Transferring Large-Scale Information from Global Climate Models to the Catchment Scale

Teutschbein, Claudia January 2013 (has links)
A changing climate can severely perturb regional hydrology and thereby affect human societies and life in general. To assess and simulate such potential hydrological climate change impacts, hydrological models require reliable meteorological variables for current and future climate conditions. Global climate models (GCMs) provide such information, but their spatial scale is too coarse for regional impact studies. Thus, GCM output needs to be downscaled to a finer scale either through statistical downscaling or through dynamic regional climate models (RCMs). However, even downscaled meteorological variables are often considerably biased and therefore not directly suitable for hydrological impact modeling. This doctoral thesis discusses biases and other challenges related to incorporating climate model output into hydrological studies and evaluates possible strategies to address them. An analysis of possible sources of uncertainty stressed the need for full ensembles approaches, which should become standard practice to obtain robust and meaningful hydrological projections under changing climate conditions. Furthermore, it was shown that substantial biases in current RCM simulations exist and that correcting them is an essential prerequisite for any subsequent impact simulation. Bias correction algorithms considerably improved RCM output and subsequent streamflow simulations under current conditions. In addition, differential split-sample testing was highlighted as a powerful tool for evaluating the transferability of bias correction algorithms to changed conditions. Finally, meaningful projections of future streamflow regimes could be realized by combining a full ensemble approach with bias correction of RCM output: Current flow regimes in Sweden with a snowmelt-driven spring flood in April will likely change to rather damped flow regimes that are dominated by large winter streamflows.
346

Implications of GRACE Satellite Gravity Measurements for Diverse Hydrological Applications

Yirdaw-Zeleke, Sitotaw 09 April 2010 (has links)
Soil moisture plays a major role in the hydrologic water balance and is the basis for most hydrological models. It influences the partitioning of energy and moisture inputs at the land surface. Because of its importance, it has been used as a key variable for many hydrological studies such as flood forecasting, drought studies and the determination of groundwater recharge. Therefore, spatially distributed soil moisture with reasonable temporal resolution is considered a valuable source of information for hydrological model parameterization and validation. Unfortunately, soil moisture is difficult to measure and remains essentially unmeasured over spatial and temporal scales needed for a number of hydrological model applications. In 2002, the Gravity Recovery And Climate Experiment (GRACE) satellite platform was launched to measure, among other things, the gravitational field of the earth. Over its life span, these orbiting satellites have produced time series of mass changes of the earth-atmosphere system. The subsequent outcome of this, after integration over a number of years, is a time series of highly refined images of the earth's mass distribution. In addition to quantifying the static distribution of mass, the month-to-month variation in the earth's gravitational field are indicative of the integrated value of the subsurface total water storage for specific catchments. Utilization of these natural changes in the earth's gravitational field entails the transformation of the derived GRACE geopotential spherical harmonic coefficients into spatially varying time series estimates of total water storage. These remotely sensed basin total water storage estimates can be routinely validated against independent estimates of total water storage from an atmospheric-based water balance approach or from well calibrated macroscale hydrologic models. The hydrological relevance and implications of remotely estimated GRACE total water storage over poorly gauged, wetland-dominated watershed as well as over a deltaic region underlain by a thick sand aquifer in Western Canada are the focus of this thesis. The domain of the first case study was the Mackenzie River Basin wherein the GRACE total water storage estimates were successfully inter-compared and validated with the atmospheric based water balance. These were then used to assess the WATCLASS hydrological model estimates of total water storage. The outcome of this inter-comparison revealed the potential application of the GRACE-based approach for the closure of the hydrological water balance of the Mackenzie River Basin as well as a dependable source of data for the calibration of traditional hydrological models. The Mackenzie River Basin result led to a second case study where the GRACE-based total water storage was validated using storage estimated from the atmospheric-based water balance P-E computations in conjunction with the measured streamflow records for the Saskatchewan River Basin at its Grand Rapids outlet in Manitoba. The fallout from this comparison was then applied to the characterization of the Prairie-wide 2002/2003 drought enabling the development of a new drought index now known as the Total Storage Deficit Index (TSDI). This study demonstrated the potential application of the GRACE-based technique as a tool for drought characterization in the Canadian Prairies. Finally, the hydroinformatic approach based on the artificial neural network (ANN) enabled the downscaling of the groundwater component from the total water storage estimate from the remote sensing satellite, GRACE. This was subsequently explored as an alternate source of calibration and validation for a hydrological modeling application over the Assiniboine Delta Aquifer in Manitoba. Interestingly, a high correlation exists between the simulated groundwater storage from the coupled hydrological model, CLM-PF and the downscaled groundwater time series storage from the remote sensing satellite GRACE over this 4,000 km2 deltaic basin in Canada.
347

Polymer-based treatments to control runoff, leachate and erosion from engineered slopes at Simfer Mine, Guinea, Africa

Campbell, Stephanie January 2013 (has links)
It is necessary to understand the erodibility and hydrological response of mine-site slope forming materials (SFMs), because of increasing awareness of the environmental impacts of mining. Steep engineered slopes in high intensity rainfall environments present a serious erosion risk. Temporary surface stabilisers, such as polyacrylamides (PAMs) and polyvinylacrylic latex (PVALs) are potentially cost effective erosion control solutions. In this study PAM and PVAL efficacy to reduce runoff, leachate and erosion was assessed at two application rates, with and without gypsum on SFMs from an iron ore mine in Guinea (West Africa). NSPASS (near-surface photogrammetry assessment of slope forming materials’ surface roughness) is a novel method that integrates digital image capture and GIS. It is shown to detect and quantify surface micro-relief changes of 2-3 mm, not visible to the naked eye. As expected, soil and non-soil SFMs were significantly different in terms of their physical and chemical properties. Phase I of the study investigated the erodibility of ten SFMs, including soil, ore and waste-rock. The results indicate that the hydrological response to rainfall of most SFMs is to generate leachate. Weathered phyllite (PHY-WEA) is the most erodible SFM by both runoff and leachate. Multiple regression analysis demonstrated that magnetic susceptibility, mineralogy and dry aggregate distribution; parameters not commonly assessed in erosion studies, are important in explaining SFM erodibility and hydrological response. Phase II evaluated critically the effectiveness of three commercially available polymer solutions (two PAMs and one PVAL) at reducing runoff, leachate and erosion from four of the most erodible SFMs identified in Phase I. The results indicate that some PAM and PVAL treatments significantly reduce runoff, leachate and erosion. Polymer efficacy is highly dependent on the physical and chemical properties of the SFM, as well as the mechanism of polymer to SFM adsorption. Increasing the application rate of select treatments lowered leachate volumes, runoff and leachate total sediment loads. Contrary to previous studies, gypsum amendments did not significantly improve polymer efficiency. This research has added to our understanding of the erodibility and hydrological response of soil and non-soil SFMs. This is the first study to evaluate critically the efficacy of PVALs in controlling erosion from mine-site SFMs. Future studies should continue to optimise NSPASS performance in monitoring changes in surface micro-relief.
348

Implications of GRACE Satellite Gravity Measurements for Diverse Hydrological Applications

Yirdaw-Zeleke, Sitotaw 09 April 2010 (has links)
Soil moisture plays a major role in the hydrologic water balance and is the basis for most hydrological models. It influences the partitioning of energy and moisture inputs at the land surface. Because of its importance, it has been used as a key variable for many hydrological studies such as flood forecasting, drought studies and the determination of groundwater recharge. Therefore, spatially distributed soil moisture with reasonable temporal resolution is considered a valuable source of information for hydrological model parameterization and validation. Unfortunately, soil moisture is difficult to measure and remains essentially unmeasured over spatial and temporal scales needed for a number of hydrological model applications. In 2002, the Gravity Recovery And Climate Experiment (GRACE) satellite platform was launched to measure, among other things, the gravitational field of the earth. Over its life span, these orbiting satellites have produced time series of mass changes of the earth-atmosphere system. The subsequent outcome of this, after integration over a number of years, is a time series of highly refined images of the earth's mass distribution. In addition to quantifying the static distribution of mass, the month-to-month variation in the earth's gravitational field are indicative of the integrated value of the subsurface total water storage for specific catchments. Utilization of these natural changes in the earth's gravitational field entails the transformation of the derived GRACE geopotential spherical harmonic coefficients into spatially varying time series estimates of total water storage. These remotely sensed basin total water storage estimates can be routinely validated against independent estimates of total water storage from an atmospheric-based water balance approach or from well calibrated macroscale hydrologic models. The hydrological relevance and implications of remotely estimated GRACE total water storage over poorly gauged, wetland-dominated watershed as well as over a deltaic region underlain by a thick sand aquifer in Western Canada are the focus of this thesis. The domain of the first case study was the Mackenzie River Basin wherein the GRACE total water storage estimates were successfully inter-compared and validated with the atmospheric based water balance. These were then used to assess the WATCLASS hydrological model estimates of total water storage. The outcome of this inter-comparison revealed the potential application of the GRACE-based approach for the closure of the hydrological water balance of the Mackenzie River Basin as well as a dependable source of data for the calibration of traditional hydrological models. The Mackenzie River Basin result led to a second case study where the GRACE-based total water storage was validated using storage estimated from the atmospheric-based water balance P-E computations in conjunction with the measured streamflow records for the Saskatchewan River Basin at its Grand Rapids outlet in Manitoba. The fallout from this comparison was then applied to the characterization of the Prairie-wide 2002/2003 drought enabling the development of a new drought index now known as the Total Storage Deficit Index (TSDI). This study demonstrated the potential application of the GRACE-based technique as a tool for drought characterization in the Canadian Prairies. Finally, the hydroinformatic approach based on the artificial neural network (ANN) enabled the downscaling of the groundwater component from the total water storage estimate from the remote sensing satellite, GRACE. This was subsequently explored as an alternate source of calibration and validation for a hydrological modeling application over the Assiniboine Delta Aquifer in Manitoba. Interestingly, a high correlation exists between the simulated groundwater storage from the coupled hydrological model, CLM-PF and the downscaled groundwater time series storage from the remote sensing satellite GRACE over this 4,000 km2 deltaic basin in Canada.
349

Modelling Hydrological and Hydrodynamic Processes in Lake Tana Basin, Ethiopia

Setegn, Shimelis Gebriye January 2010 (has links)
Lake Tana Basin is of significant importance to Ethiopia concerning water resources aspects and the ecological balance of the area. The growing high demands in utilizing the high potentials of water resource of the Lake to its maximal limit, pictures a disturbing future for the Lake. The objective of this study was to assess the influence of topography, soil, land use and climatic varia-bility on the hydrological and hydrodynamic processes of the Lake Tana Basin. The physically based SWAT model was successfully calibrated and validated for flow and sediment yield. Se-quential uncertainty fitting (SUFI-2), parameter solution (ParaSol) and generalized likelihood un-certainty estimation (GLUE) calibration and uncertainty analysis methods were compared and used for the set-up of the SWAT model. There is a good agreement between the measured and simulated flows and sediment yields. SWAT and GIS based decision support system that uses multi-criteria evaluation (MCE) was used to identify the most vulnerable areas to soil erosion in the basin. The results indicated that 12 to 30.5% of the watershed is high erosion potential. Pro-jected changes in precipitation and temperature in the basin for two seasons were analyzed using outputs from fifteen global climate models (GCMs). A historical-modification procedure was used to downscale large scale outputs from GCM models to watershed-scale climate data. The results showed significant changes in streamflow and other hydrological parameters in the period between 2045-2100. SWAT was combined with a three dimensional hydrodynamic model, GEMSS to investigate the flow structure, stratification, the flushing time, lake water balance and finally the Lake‘s water level response to planned water removal. We have found an alarming and dramatic fall of the water levels in Lake Tana as response to the planned water withdrawal. The combination of the two models can be used as a decision support tools to better understand and manage land and water resources in watersheds and waterbodies. The study showed that the Lake Tana Basin may experience a negative change in water balance in the forthcoming decades due to climate change as well as over abstraction of water resources. / QC 20100720
350

Nitella congesta - a charophyte as a tool for the rehabilitation of sand mine-void wetlands at Capel, Western Australia

Annan, Isaac Kwamina Eshun January 2008 (has links)
This research is the outcome of investigations of the ability of Nitella congesta, a charophyte, to hyperaccumulate metal contaminants, as well as contribute to the sustainable development of a chain of lakes derived from the sand mine voids at Capel 250km south of Perth, Western Australia. Studies were conducted to ascertain the taxonomy of Nitella congesta as well as its life cycle pattern in relation to the hydrological regime of the lakes of the wetlands. It was observed that a decrease in the availability of water in the lakes particularly on the onset of summer, initiated the production of fruiting bodies whiles prolonged availability of water ensured a prolonged vegetative growth. / Aquatic plants play an important role in the structuring of freshwater communities. Freshwater macrophytes such as Nitella congesta have been reported to serve as food source as well as provide refuge and shelter for macroinvertebrates. Thus the presence of freshwater macrophytes in one way or the other has a direct impact on the species abundance and diversity of macroinvertebrates that use them as their habitat. A study of the impact of Nitella congesta as a suitable macrophyte on diversity and abundance of macroinvertebrates showed a positive outcome. It was observed that species richness and diversity were high in Nitella congesta dominated sites of the lakes. Experimental outcome showed that Nitella congesta is a hyperaccumulator of metals. Both the mucilage and the thallus displayed concentrations of few metals. / The disappearance of submerged macrophytes such as charophytes in shallow lakes is a major problem caused by eutrophication. There has been an approved proposal to discharge treated waste water with a phosphorus concentration of about 4,000μg/L into the lakes of the Capel Wetlands Centre. This necessitated a study of the impact of eutrophication on the establishment of Nitella congesta as a functional macrophyte for the enhancement of the ecological structure of the wetlands. / Results showed that though eutrophication will initially increase the primary productivity of the lakes of the wetlands, the eventual consequence will be the loss of Nitella congesta as a functional macrophyte in the wetlands. / At the last stage of the study, a consistent decrease in pH readings of the lakes and lack of successful germination of Nitella congesta as a result of prolonged drought and exposure of the lake sediment was observed. This necessitated a thorough study of the impact of climate change on the establishment of Nitella congesta in the wetlands. In conclusion, it was observed that Nitella congesta could serve as a suitable tool for the rehabilitation of the wetlands.

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