Through distributed stream network routing, it has quantitatively been shown that the relationship between flow travel time and discharge varies strongly nonlinearly with stream stage and with catchment-specific properties. Physically derived distributions of water travel times through a stream network were successfully used to parameterise the streamflow response function of a compartmental hydrological model. Predictions were found to improve compared to conventional statistically based parameterisation schemes, for most of the modelled scenarios, particularly for peakflow conditions. A Fourier spectral analysis of 55-110 years of daily discharge time series from 79 unregulated catchments in Sweden revealed that the discharge power spectral slope has gradually increased over time, with significant increases for 58 catchments. The results indicated that the catchment scaling function power spectrum had steepened in most of the catchments for which historical precipitation series were available. These results suggest that (local) land-use changes within the catchments may affect the discharge power spectra more significantly than changes in precipitation (climate change). A case study from an agriculturally intense catchment using historical (from the 1880s) and modern stream network maps revealed that the average stream network flow distance as well as average water levels were substantially diminished over the past century, while average bottom slopes increased. The study verifies the hypothesis that anthropogenic changes (determined through scenario modelling using a 1D distributed routing model) of stream network properties can have a substantial influence on the travel times through the stream networks and thus on the discharge hydrographs. The findings stress the need for a more hydrodynamically based approach to adequately describe the variation of streamflow response, especially for predictions of higher discharges. An increased physical basis of response functions can be beneficial in improving discharge predictions during conditions in which conventional parameterisation based on historical flow patterns may not be possible - for example, for extreme peak flows and during periods of nonstationary conditions, such as during periods of climate and/or land use change. / <p>QC 20150903</p>

L’évaluation du débit en réseaux hydrauliques à surface libre est une problématique actuelle sur le plan scientifique, à forts enjeux technologiques, économiques et écologiques. Dans cette thèse, de nouvelles méthodologies d’instrumentation, basées sur une synergie entre mesures non intrusives de hauteur d’eau et modélisation numérique ont été développées. Celles-ci s’appliquent d’une part à des collecteurs dont le fonctionnement hydraulique est complexe et, d’autre part, à des ouvrages non-standard (Venturi, déversoirs d’orage). Ce travail de thèse multidisciplinaire vise une meilleure compréhension de l’écoulement pour en déduire des relations Q=f(hi) plus robustes, spécifiques à chaque site et associées à leurs incertitudes; mais également l’identification de possibles modifications du site de mesure afin d’améliorer l’estimation du débit. Au final, l’applicabilité des méthodologies développées a été éprouvée au travers de plusieurs études sur sites réels. / The evaluation of the flow rate in free surface water systems is a current scientific problem, related to high technological, economical and ecological issues. In this study, new methods of instrumentation based on a synergy between non-intrusive water level measurements and numerical modeling have been developed. These methods are applied first to sewer pipes with complex hydraulic conditions then to non-standard hydraulic structures (Venturi flumes, Combined Sewer Overflows). This multidisciplinary work aims at a better understanding of the flow to identify more robust site-specific Q=f(hi) relationships related to their uncertainties. It also aims at the identification of possible modification of the measurement site in order to improve the flow rate evaluation. Finally, the applicability of the developed methodologies has been tested through several real site studies.

This thesis is a study of flood protection in the community Želešice, Brno-venkov. The theoretical part deals with: the causes of flooding, their dividing and deals with options, how to protect endangered area. Main part includes calculations of the amount of sediment in the river Bobrava and the Hajanský stream, analysis of risks by quantitative expression, suggests to complete the flood plan of the community and a list of designed flood control measures with own technical suggestion. The last point is to consider, whether is the community threatened by backwater from the river Svratka, which the river Bobrava flows into.

Shire of Murray has concerns regarding the negative impact that a 100 year flood could have on existing structures built before 1997. The increase cost in construction due to landfill has an adverse effect on development in Pinjarra. Feasibility of constructing a diversion channel at upstream of Murray River to attenuate the flood level from 1 in 100 year ARI to 1 in 50 year ARI, was investigated by Kiong (2003). The Murray River Water Surface Profile along three kilometres south of Greenlands Road was modelled. Flood damages on each flood occurrence were assessed and Average Annual Damage (AAD) was calculated. The AAD is used to estimate the monetary benefit against the construction cost of the diversion channel. Groundwater along Greenlands and Fauntleroy Drains was also modelled to determine the viable depth of the designed channel, as well as the analysis of backwater. The proposed channel is designed at different scenarios (invert level at breakout point, culvert or causeway design, and diversion channel variations). The benefit cost ratio of the proposed diversion channel is calculated. Other mitigation options are suggested including detention basins for structural measure, or building a new flood-proof township for non-structural measure.