Date of Award

2014

Document Type

Master Thesis

Degree Name

Master of Engineering (Research)

Department

Civil, Structural and Environmental Engineering

First Advisor

Dr. Joseph Harrington

Abstract

Suspended sediment is a key contributor to contaminant transfer within river systems. The relationship between the transport of suspended sediment and nutrients influences the status of water quality and sustainability of aquatic habitats. This thesis studies suspended sediment and nutrient transport on the River Bandon.

This thesis includes a literature review of suspended sediment and nutrient transport, appropriate legislation, river flow representation and flood frequency estimation.

As part of a structured field monitoring programme, manual samples have been collected periodically and tested for suspended sediment concentration (SSC), turbidity, five species of phosphorus and five species of nitrogen. Continuous in-situ turbidity monitoring has also been undertaken using a submersed turbidity probe.

Suspended sediment and nutrient analysis are presented. Relationships between SSC, turbidity, nutrients and flow rates have been developed to find suitable surrogate parameters for a continuous monitoring programme. Turbidity was found to be an excellent surrogate for SSC (R2 = 0.86) and total phosphorus (TP) (R2 = 0.88). The annual estimated and true suspended sediment loads for the catchment arc 4988 tonnes and 7393 tonnes respectively. The estimated and true annual loads have been quantified for each of the phosphorus and nitrogen species using ratio estimator and linear regression techniques, fhe annual total phosphorus and total nitrogen loads were estimated at 36.8 tonnes and 1065 tonnes respectively. Results show that 63% of the phosphorus samples are above the EU guideline eutrophication limit of 0.03 mg/1 P indicating that the river is moderately polluted.

Specific storm events have been assessed. Event based monitoring and hysteretic relationships have been applied to assess the influence of the storm events on suspended sediment and nutrient transport. Results show that 95% of the annual suspended sediment load is transported in the four highest flood events of a year.

Access Level

info:eu-repo/semantics/openAccess

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