No description available.

No description available.

Thesis (M.A.)--York University, 2004. Graduate Programme in Geography. / Typescript. Includes bibliographical references (leaves 158-172). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ99284

<p>The hydrological processes of the active layer in continuous permafrost areas are governed by water and energy fluxes, with most hydrological activities concentrated in the thawed seasons. This study was focused on the modelling of hydrological processes in the active layer, emphasizing the fluctuations of the frost table and the moisture status in the thawed zone. Emphases were placed on the calibration of a one-dimensional hydrological model and the development of a two-dimensional model to simulate frost table descent during the summer time. Woo and Drake (1988) developed a model to simulate the daily hydrological and thermal processes of a vertical column in continuous permafrost areas. It combines freeze-thaw processes with water balance to enable daily updating of the status of the frost table, water table, soil moisture, snowmelt and evaporation. Input data include only precipitation, global solar radiation, and air temperature. This model has not been calibrated for the High Arctic and only limited field testing has been performed. This study used field measurements from Resolute, Northwest Territories, to calibrate the model. Independently by obtained data sets were used to test the model outputs and compared with field measurements. The model performed well. The model was then applied to simulate the hydrological responses to climatic variability. The sensitivity of the model was analyzed and discussed. The frost table represents the dynamic lower boundary of the thawed zone. The horizontal variation in frost table depth was modeled, applying the Green theorem to solve the heat flow equation for the active layer zone where the 0$\sp\circ$C isotherm is the limit of thaw. This model incorporates the effect of ground ice content in the retardation of thawing front descent, and the moisture status in the calculation of thermal conductivity. The frost table computed for a transect comprising two distinct soil segments compared favourably with field measured values. The model was used to assess frost table responses to varying degrees of soil saturation, ice content and air temperatures. This model was also coupled to the outputs from the one-dimensional model to allow horizontal extension of the frost table simulations. Coupling of these two models enable hydrological simulation of continuous permafrost terrain using limited input data that can be obtained from Arctic Weather Stations.</p> / Doctor of Philosophy (PhD)

A preliminary hydrologic investigation of Topock Marsh, located in northwestern Arizona, was conducted for the U.S. Fish and Wildlife Service between 1995 and 1998. The study identified the hydrological components of the marsh system, quantified an annual water budget, defined the water quality conditions of the open-water marsh, examined water management concerns, and provided data for a concurrent submersed aquatic vegetation (SAV) study. The water budget tabulated monthly values for all hydrologic components except net ground-water flow, which was determined by difference. The principal components were river inflow (+60,020 ± 1,020 ac-f1), rainfall (+890 ± 40 ac-f1), evapotranspiration (-28,170 ± 940 ac-fl), storage (-980 ± 30) and marsh outflow (-26,860 ± 890 ac-f1). The net ground-water value (-6,960 ± 1,650 ac-f1) suggests that the marsh recharges ground-water. The Refuge also exceeded its diversion and consumptive use entitlement. Water quality conditions were assessed using continuous and discrete sampling methods. Three in-situ devices measured routine water quality parameters (temperature, pH, conductivity, dissolved oxygen, oxidation-reduction potential) for two years. Quarterly water samples (1997-98) from four marsh sites were analyzed for major and select minor ions, and δ¹⁸O- δD values. The continuously monitored parameters exhibited, to varying degrees, temporal (diurnal and seasonal) and spatial variability. The marsh was well mixed and has oxygen levels capable of supporting most aquatic life. Evaporative concentration was the major process controlling major ion chemistry. Isotope data confirmed that the marsh and nearby shallow ground-water derive from a river-water source. The marsh is normally turbid (30 NTU), apparently resulting from the resuspension of detrital material by wind-generated waves. The turbidity values dropped below 5 NTU during the 1996 summer as dense patches of SAV "filtered" the water. Light penetration is probably a limiting factor controlling the distribution of SAV in the marsh. Today's water management plan is the culmination of historical practices, incomplete science, institutional goals, and other constraints. Together these factors have led to relatively static hydrologic conditions in the marsh. Potentially negative consequences can result from the continuance of traditional management, including loss of diversity, accelerated in-filling, and salinization. The Refuge should consider simulating disturbances (e.g., flooding) and developing a more complex water management plan.

This thesis examines both surface water and shallow groundwater connections in boreal watersheds at two study sites in the Athabasca Oil Sands Region using conventional hydrological techniques as well as stable water isotope techniques. Increased emissions due to oil sands development are expected to contribute significantly to acidifying airborne emissions. Specifically, nitrogen is forecasted to be deposited on the surrounding area within approximately 100 km of operations. The purpose of the research is to provide background information for predicting how individual terrain units such as fens, bogs, and uplands will respond to increased nitrogen loads, and to assess whether or not these units will act as sources or sinks of nitrogen under higher nitrogen deposition. Two study sites situated within 100 km of Fort McMurray, Alberta were instrumented with a total of 30 nested piezometers, 26 water table wells, 4 micro-meteorological stations, and two gauging stations (weirs) at outflow points. Monitoring occurred during the open water season of 2011 and 2012. This study estimates evaporation through a simplified energy balance, documents hydraulic conductivity of shallow aquifers, utilizes stable isotopes of water to assist in mapping seasonal flow patterns, and calculates a vertical water balance for the sites. Bogs and fens were hydrologically connected, as bogs fed fens laterally at shallow depths within the acrotelm during wet years. Upland terrain units were found to have more variable connections. In spring, upland runoff recharged the wetlands at both sites. At JPH groundwater flowed towards the fen, whereas in ML limited connections were observed between the uplands and the fen. Also, no connections were seen to indicate that the wetlands recharged the uplands. A conceptual model is developed that emphasizes the role of connectivity in the boreal landscape. The main implication for nitrogen cycling is that it is difficult to quantify one landscape as a source or sink for additional nitrogen as its role may vary depending on seasonality and temporal scales. Further work is needed to identify if nitrogen loadings will have adverse affects on geochemistry of water at the sites. / Graduate / 0366 / amyvallarino@gmail.com

The study aims to provide a framework for the quantitative evaluation of the water resources on a regional basis. The work involves hydrologic data augmentation and analysis of the water budget of the Central Luzon Basin, a humid, tropical region. Four hydrologic data augmentation methodologies -- percent deviation, HEC-4, YOR, and Matalas-Jacobs -- were analyzed and compared. Streamflow data of five gaging stations in the Central Luzon Basin were divided into early-half and late-half series. Augmentation estimates based on the late-half series were compared with the corresponding historical early-half series. The methods were assessed based on eight comparison items and two scoring systems. The comparison items considered were double mass analysis, mean, cumulative annual deviations, and standard deviations, for the annual flows; and maximum, minimum, mean, and standard deviations, for the monthly flows. The percent deviation method excelled in both scoring systems and was selected as the best method for the hydrological characteristics and type of available data in the region. Application of the percent deviation method in augmenting the record of selected streamflow gaging stations within the Central Luzon Basin pointed out some limitations of the method. These limitations may be remedied by proper selection of the station on which the augmentation estimates are based. Strong statistical relationship between the dependent and base stations, in addition to other hydrological factors, should be satisfied for the derivation of more reliable estimates in the application of the percent deviation to streamflow data augmentation. The water budget analysis revealed that about 54 percent of the annual precipitation in the basin is measured as streamflow. The balance of 46 percent is shared by evapotranspiration and change in basin storage. An average annual evapotranspiration of about 1,070 mm was found. This is about 0.5 of the average Class A pan evaporation data from two measurement points. Surface water resources remain the most important source of water for the basin requirements. No serious water quality problems exist and surface water in the basin is suitable for both domestic and agricultural purposes. Groundwater could be a promising alternative resource for both domestic and agricultural uses. High recharge during the rainy season, about 5,000 to 7,000 MCM, and relatively shallow aquifers are among the significant features of the groundwater basin.

<p>Even though dams are designed to bypass floods of significant magnitudes, floods less severe than the design flood may pose a threat to dams. Ongoing research into climate change also shows an increasing trend towards severe floods, that is an increased probability of floods exceeding the present design floods. Therefore, acquiring understanding of floods and risk reduction measures to mitigate any of their undesired effects is of great importance. Dam safety management in Norway has moved towards active use of risk analyses. At the same time, emergency planning and exercises are emphasized as necessary tools for handling abnormal situations such as severer floods. Few dam safety experts or dam owners have experienced large floods, which makes it difficult to assess the complexity of floods. Floods may also be difficult to assess fully by means of traditional risk analyses, as these normally focus on single dams. Floods have a certain geographical extent and must be expected to occur simultaneously in a system of dams and reservoirs. </p><p>This thesis hopes to extend knowledge of floods and dam safety. The main conclusion of a literature review of risk analysis and emergency planning is that human factors must be a focus. This is further supported by findings from the case studies of hazard floods. Emergency planning and exercises are believed to be of major importance to successful flood handling, but a survey of status for these issues in Norway shows that there is still work to be done. Many dam owners have not managed to start developing emergency action plans nor carry out emergency exercises. Not surprisingly, most of these are municipalities and private citizens, typical owners of smaller dams. Further revision of the emergency planning guidelines should take these findings into consideration. The authorities should bear in mind the need for alternative approaches to encourage these dam owners to develop emergency action plans. Possible problems related to development trends in our society also deserve attention, such as increased focus on cost-effective organizations at the expense of safety and the need for robust organizations and technical systems to handle future emergencies. </p>

Even though dams are designed to bypass floods of significant magnitudes, floods less severe than the design flood may pose a threat to dams. Ongoing research into climate change also shows an increasing trend towards severe floods, that is an increased probability of floods exceeding the present design floods. Therefore, acquiring understanding of floods and risk reduction measures to mitigate any of their undesired effects is of great importance. Dam safety management in Norway has moved towards active use of risk analyses. At the same time, emergency planning and exercises are emphasized as necessary tools for handling abnormal situations such as severer floods. Few dam safety experts or dam owners have experienced large floods, which makes it difficult to assess the complexity of floods. Floods may also be difficult to assess fully by means of traditional risk analyses, as these normally focus on single dams. Floods have a certain geographical extent and must be expected to occur simultaneously in a system of dams and reservoirs. This thesis hopes to extend knowledge of floods and dam safety. The main conclusion of a literature review of risk analysis and emergency planning is that human factors must be a focus. This is further supported by findings from the case studies of hazard floods. Emergency planning and exercises are believed to be of major importance to successful flood handling, but a survey of status for these issues in Norway shows that there is still work to be done. Many dam owners have not managed to start developing emergency action plans nor carry out emergency exercises. Not surprisingly, most of these are municipalities and private citizens, typical owners of smaller dams. Further revision of the emergency planning guidelines should take these findings into consideration. The authorities should bear in mind the need for alternative approaches to encourage these dam owners to develop emergency action plans. Possible problems related to development trends in our society also deserve attention, such as increased focus on cost-effective organizations at the expense of safety and the need for robust organizations and technical systems to handle future emergencies.

Thesis (M.S.)--OGI School of Science & Engineering at OHSU, 2003. / Includes bibliographical references (leaves 64-71).