Identifier

etd-07032007-152113

Degree

Master of Science in Civil Engineering (MSCE)

Department

Civil and Environmental Engineering

Document Type

Thesis

Abstract

The objective of this thesis was to determine the effectiveness of hydraulic geometry curves for designing bankfull floodplains to stabilize urban streams. In stable streams bankfull discharge is contained within the stream's banks. Higher flows spread out onto the floodplain where the water's velocity drops due to the increase in area and vegetation. This dissipation of energy promotes sediment deposition, decreases flow velocity, and reduces channel erosion. In cases like Galbraith Drain where historical gage data are not available and bankfull indicators are not present, a degraded stream's bankfull depth may be estimated with hydraulic geometry curves. Over forty cross sections were taken at fifteen rivers and streams within the region of Galbraith Drain. These data were processed, and the resultant hydraulic geometry curves developed through linear regression were used to design the study reach's channel and floodplain geometry. Suspended solids concentration (SSC) was selected as the parameter by which the effectiveness of the design was measured. Optical meters were installed at the upstream and downstream ends of the study reach to continuously record stage and turbidity. Turbidity was converted to SSC from regression analysis of laboratory tested SSC samples collected at each meter location. Data collected from cross sections and slope profiles taken at the meter locations were used with Manning's equation to convert stage data to flowrates. Two methodologies were utilized to analyze the percent difference in SSC from the upstream to downstream meter. In the mass versus mass analysis, all pre- and post-construction data were plotted as SSC (kg) versus volume (ft3), from which linear regression equations were obtained. By entering the largest common volume into these equations, decreases in SSC of 2.4% and 29.9% were calculated for the pre- and post-construction conditions, respectively. For the statistical analysis, an Analysis of Covariance was performed with SAS software. When the mean SSC value (as concentration) was entered into the SAS-generated equations, an SSC increase of 29.4% resulted for pre-construction, while a decrease of 25.3% resulted for post-construction. Thus, the improvement resulting from the construction of the bankfull floodplain, as demonstrated by both analysis methodologies, is definitive and significant.

Date

2007

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Vijay P. Singh

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