Bibliography: pages 131-139. / The construction of bridge embankments and other physical obstacles in estuaries has often resulted in the redistribution of sediments, which ultimately leads to detrimental impacts in these environments. The aim of this study is to investigate how the sediment distribution and dynamics within a specific estuary, the Uilkraals estuary, have been affected by human disturbance; focusing on the impacts arising from construction of two temporary embankments and a permanent bridge and embankment. The Uilkraals estuary is situated in the south-western Cape, approximately 60 kilometres north-west of Cape Agulhas. Human impact has been extensive and engineering projects of various sizes and permanence have marked the recent history of this estuary. A bridge and embankment which cross the estuary 800 m from the mouth were built in 1973. In 1978 an embankment was built between the bridge and the estuary mouth. A second embankment which replaced the first in 1980, was removed before the end of that year. Extensive dune reclamation occurred on the left bank between 1938 and 1973. The techniques used in the study include: (i) a quantitative analysis of all available aerial photographs from 1938 to 1987 (ii) a ground survey and (iii) core and surface sediment sampling. The quantitative analysis reveals that the major changes in estuarine characteristics have been in response to human disturbance. The contour map and cross-sections drawn from the ground survey indicate a build-up of sediment downstream of the bridge and scouring of the channel upstream. The latter suggests the dominance of the flood-tidal current in the estuary. The core sediment analyses are unable to distinguish any real difference in the modes of sediment deposition on either side of the bridge embankment. The embankment has, however, affected deposition by acting as a "hydraulic shelter" to sediment accumulated downstream of the bridge during high run-off events and by initiating deposition of sediment upstream of the embankment. The surface sample analyses indicate that there has been an increase in flow velocities in the vicinity of the bridge since its construction and that the major agents which bring marine sediment into the estuary are flood-tidal currents and wind. It is concluded that the sediment distribution and dynamics of the Uilkraals estuary have been affected by human disturbance. Recommendations for future management of the estuary are that no further embankments should be constructed in the estuary and that the construction of a culvert or culverts under the existing bridge embankment would alleviate a number of problems presently experienced in the estuary.

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While release of contaminants during dredged material disposal operations has long been the subject of environmental concern, the potential release of pollutants during the dredging process has recently come under the scrunity of federal and state regulatory agencies. The mechanical action of a dredging operations causes resuspension of sediment particles and release of soluble contaminants to the water column. A predredging test is essential to estimate the amount of soluble release at or near the point of dredging to ascertain potential water quality impact. The Standard Elutriate Test has proven to be a good estimator of soluble contaminant release for dredged material disposal operations and researchers have recognized that the processes involved at the point of dredging are similar to those involved with the open-water disposal of dredged material. This research is an evaluation of the Standard Elutriate Test as an estimator of soluble contaminant release at the point of dredging. Data and field studies were conducted by the U.S. Army Corps of Engineers Waterways Experiment Station at five sites around the United States. A direct comparison was made between elutriate test data from predredging bottom sediment and water sample analysis taken at or near the point of dredging. The Standard Elutriate Test satisfactorily predicted the release of soluble contaminants at or near the point of dredging in four out of the five sites in this study. The fifth site had extenuating circumstances that may account for the failure at this site. In this investigation, the elutriate test appears to overestimate the release of organics, nutrients and some heavy metals (Hg, Mn, Fe, and Cr). Statistical analysis provided a predictive equation that can be used to estimate the upper-bound value a constituent concentration will approach based on elutiate test data and a specified confidence level. / M.S.

Wong Chi-chun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 114-118). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / Chinese Abstract --- p.v / Table of Contents --- p.vii / List of Figures --- p.x / List of Tables --- p.xii / List of Plates --- p.xiii / Chapter Chapter 1 --- General Introduction / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Study Site --- p.1 / Chapter 1.3 --- Experimental Organisms --- p.4 / Chapter 1.4 --- Objectives --- p.8 / Chapter 1.5 --- Outline of the Thesis --- p.8 / Chapter Chapter 2 --- The Physical Parameters of AMW and AYW in Ping Chau / Chapter 2.1 --- Introduction --- p.11 / Chapter 2.2 --- Materials and Methods --- p.12 / Chapter 2.2.1 --- Sedimentation rates --- p.12 / Chapter 2.2.2 --- Particle size analysis for trapped sediments --- p.14 / Chapter 2.2.3 --- Total suspended solid --- p.14 / Chapter 2.2.4 --- Relative light penetration --- p.15 / Chapter 2.2.5 --- Statistical analysis --- p.15 / Chapter 2.3 --- Results --- p.15 / Chapter 2.3.1 --- Sedimentation rates --- p.15 / Chapter 2.3.2 --- Particle size analysis --- p.17 / Chapter 2.3.3 --- Total suspended solids --- p.21 / Chapter 2.3.4 --- Relative light penetration --- p.21 / Chapter 2.4 --- Discussion --- p.21 / Chapter 2.5 --- Summary --- p.27 / Chapter Chapter 3 --- The Growth Rates of Platygyra sinensis and Goniopora columna Under Different Sediment Load Environments / Chapter 3.1 --- Introduction --- p.28 / Chapter 3.1.1 --- Staining by Alizarin Red S --- p.29 / Chapter 3.1.2 --- X-ray radiography for growth bands --- p.31 / Chapter 3.1.3 --- Photography or Video recording --- p.39 / Chapter 3.1.4 --- Counting the number of polyps --- p.33 / Chapter 3.1.5 --- Accurate buoyant weighing technique --- p.33 / Chapter 3.1.6 --- Concrete nail --- p.34 / Chapter 3.2 --- Materials and Methods --- p.36 / Chapter 3.3 --- Results --- p.37 / Chapter 3.4 --- Discussion --- p.38 / Chapter Chapter 4 --- Sediment-rejection efficiency of Platygyra sinensis and Goniopora columna in situ and in aquarium / Chapter 4.1 --- Introduction --- p.44 / Chapter 4.2 --- Materials and Methods --- p.45 / Chapter 4.2.1 --- hi si/11 Experiment --- p.45 / Chapter 4.2.2 --- In Aquarium --- p.46 / Chapter 4.2.3 --- Statistical analysis --- p.47 / Chapter 4.3 --- Results --- p.47 / Chapter 4.3.1 --- Behavioral responses --- p.47 / Chapter 4.3.2 --- Treatment effects --- p.48 / Chapter 4.3.3 --- Convexity of Platygyra sinensis --- p.48 / Chapter 4.4 --- Discussion --- p.52 / Chapter Chapter 5 --- The Effects of Continuous Sediment Influx on Platygyra sinensis and Goniopora columna / Chapter 5.1 --- Introduction --- p.57 / Chapter 5.2 --- Materials and Methods --- p.59 / Chapter 5.2.1 --- Aquaria set-up --- p.59 / Chapter 5.2.2 --- Coral handling --- p.60 / Chapter 5.2.3 --- Preliminary screening experiment --- p.60 / Chapter 5.2.4 --- Persistent sediment influx experiment --- p.61 / Chapter 5.2.5 --- Evaluation of zooxanthellae and chlorophyll-a densities --- p.62 / Chapter 5.2.6 --- Daily weather records --- p.63 / Chapter 5.3 --- Results --- p.63 / Chapter 5.3.1 --- Preliminary screening experiment --- p.63 / Chapter 5.3.2 --- Persistent influx experiment --- p.64 / Chapter 5.3.3 --- Weather data from Hong Kong Observatory --- p.71 / Chapter 5.3.4 --- Aquaria condition --- p.71 / Chapter 5.4 --- Discussion --- p.74 / Chapter Chapter 6 --- Short-term Sediment Burial Effects on Platygyra sinensis and Goniopora columna --- p.81 / Chapter 6.1 --- Introduction --- p.81 / Chapter 6.2 --- Materials and Methods --- p.82 / Chapter 6.2.1 --- In situ burial experiments --- p.82 / Chapter 6.2.2 --- Burial experiment in aquaria --- p.84 / Chapter 6.3 --- Results --- p.85 / Chapter 6.3.1 --- Behavioral response --- p.85 / Chapter 6.3.2 --- First in situ burial experiment 一 Oct1999 --- p.85 / Chapter 6.3.3 --- Second in situ burial experiment - Jan2000 --- p.92 / Chapter 6.3.4 --- Burial experiment in aquaria - Mid-June2000 --- p.102 / Chapter 6.4 --- Discussion --- p.103 / Chapter Chapter 7 --- Summary and Perspective --- p.109 / References --- p.114

Graduation date: 1986

Thesis (Ph. D.)--Université Paul Sabatier, Toulouse III, 1975. / Map documentation: p. [I-II] (3rd set of capital Roman numerals). Includes bibliographical references (p. [I]-[XIX]).