Thesis (Ph. D.)., Memorial University of Newfoundland, 1998. / Bibliography: leaves 193-201.

Thesis (M.S.) -- University of Tennessee, Knoxville, 2005. / Title from title page screen (viewed on Feb. 2, 2006). Thesis advisor: Matthew Gray. Vita. Includes bibliographical references.

Thesis (M.S.)--Dept. of Geosciences. University of Missouri--Kansas City, 2004. / "A thesis in urban environmental geology." Typescript. Advisor: Raymond M. Coveney. Vita. Title from "catalog record" of the print edition Description based on contents viewed Feb. 27, 2006. Includes bibliographical references (leaves 77-80). Online version of the print edition.

Thesis (M.S.)--Montana State University--Bozeman, 2007. / Typescript. Chairperson, Graduate Committee: Christopher S. Guy. Includes bibliographical references (leaves 66-74).

No description available.

The Kalman Filter has been applied to many fields of hydrology, particularly in the area of flood forecasting. This recursive estimation technique is based on a state-space approach which combines model description of a process with data information, and accounts for uncertainties in a hydrologic system. This thesis deals with applications of the Kalman Filter to ARMAX models in the context of streamflow prediction. Implementation of the Kalman Filter requires specification of the noise covariances (Q, R) and initial conditions of the state vector (x₀, P₀). Difficulties arise in streamflow applications because these quantities are often not known. Forecasting performance of the Kalman Filter is examined using synthetic flow data, generated with chosen values for the initial state vector and the noise covariances. An ARMAX model is cast into state-space form with the coefficients as the state vector. Sensitivity of the flow forecasts to specification of x₀, P₀, Q, R, (which may be different from the generation values) is examined. The filter's forecasting performance is mainly affected by the combined specification of Q and R. When both noise covariances are unknown, they should be specified relatively large in order to achieve a reasonable forecasting performance. Specififying Q too small and R too large should be avoided as it results in poor flow forecasts. The filter's performance is also examined using actual flow data from a large river, whose behavior changes slowly with time. Three simple ARMAX models are used for this investigation. Although there are different ways of writing the ARMAX model in state-space form, it is found that the best forecasting scheme is to model the ARMAX coefficients as the state vector. Under this formulation, the Kalman Filter is used to give recursive estimates of the coefficients. Hence flow predictions can be revised at each time step with the latest state estimate. This formulation also has the feature that initial values of the ARMAX coefficients need not be known accurately. The noise variances of each of the three models are estimated by the method of maximum likelihood, whereby the likelihood function is evaluated in terms of the innovations. Analyses of flow data for the stations considered in this thesis, indicate that the variance of the measurement error is proportional to the square of the flow. In practice, flow predictions several time steps in advance are often required. For autoregressive processes, this involves unknown elements in the system matrix H of the Kalman model. The Kalman algorithm underestimates the variance of the forecast error if H and x are both unknown. For the AR(1) model, a general expression for the mean square error of the forecast is developed. It is shown that the formula reduces to the Kalman equation for the case where the system matrix is known. The importance of this formula is realized in forecasting situations where management decisions depend on the reliability of flow predictions, reflected by their mean square errors. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

For the six regions taken under investigation a statistical analysis of mean monthly flows was attempted. The relationship was established for all but one region. The analysis compared the coefficient of variation of the monthly flows to the size of the drainage area for each basin in a region. The regions were defined by basins of similar topography and climate. Streamflow prediction would be made by mathematical synthesis from the standard deviation parameter computed from the graphical relationships established for each region. The value of such a relationship was evidenced by the general consistency of the results. / Master of Science

No description available.

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1982. / Includes bibliographical references (leaves 78-79).

Thesis (M.Eng.)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: This study entailed the investigation and evaluation of a new methodology for measuring high discharges passing through bridges. Pressure differences generated around bridge piers have been measured and related to the discharges. These pressure differences are mainly functions of downstream flow conditions. The pressure differences have been converted into velocities by applying Newton's second law expressed in terms of the laws of conservation of energy; momentum; and of power. The energy principle was re-evaluated following a preVIOUSstudy (Retief, 1999) on a limited number of model pier combinations and flow conditions. Comparison of the energy approach with newly developed theories in terms of the momentum and power laws respectively led to the conclusion that the energy principle gave the best results. The question of applicability of the theory to practical pier/stream width and length ratios as well as its validity under flow conditions commonly found under flood conditions required that additional laboratory tests be done. The energy-based discharge equation was calibrated in terms of newly selected measuring points, different pier width and length ratios, as well as pier rotations for both super and sub-critical downstream conditions. According to the new tests performed at the Hydraulics Laboratory of the University of Stellenbosch on model piers, clear relationships were found between discharges and pressure differences measured against the pier. Calibration curves for practical flow measurement application were derived in terms of principle dimensionless parameters. Application of the energy approach at the prototype level needs further investigation. / AFRIKAANSE OPSOMMING: Hierdie studie het behels die ondersoek en evaluering van 'n nuwe metode om hoë vloeie verby brïïe te meet. Drukverskille wat rondom brug pylers opgewekword is gemeet en omgeskakel na vloeie. Hierdie drukverskille is hoofsaaklik funksies van die stroomaf vloei toestande. Die drukverskille is omgeskakel na vloeisnelhede deur die toepassing van Newton se tweede wet, uitgedruk in terme van die behoud van energie, momentum so wel as drywing. Die energie beginsel is weer geëvalueer sedert 'n vorige studie (Retief, 1999) gedoen is op 'n beperkte aantal model pylerkombinasies en vloeitoestande. Hierdie energie-benadering is met nuwe metodes vergelyk, naamlik die momentum en drywings wette. Die gevolgtrekking is gemaak dat die energie metode die beste resultate gee. Die vraag oor die toepaslikheid van die teorie met praktiese pyler/stroom wydte en lengte verhoudings so wel as die toepaslikheid hiervan onder die vloei toestande wat algemeen onder vloedtoestande voorkom het addisionele laboratoriumtoetse vereis. Die energie gebaseerde vloeivergelyking is gekalibreer in terme van nuut geselekteerde meetpunte, verskillende pyler wydte en lengte verhoudings, asook pyler rotasies vir beide super en sub-kritiese stroomaf toestande. Na aanleiding van die toetse gedoen in die Hidroulika Laboratorium van die Universiteit van Stellenbosch op brugpylers, is duidelike verbande gekry tussen die vloeie en die drukverskille soos gemeet teen die pyler. Kalibrasie-kurwes vir die toepassing van praktiese vloeimeting is ontwikkel in terme van die toepassing van dimensielose parameters. Die toepassing van die energiebenadering op prototipe vlak verg verdere ondersoek.