Open coastlines are dynamic environments which experience seasonal and long-term physical changes. Sandy beaches line much of this coastline. As part of the requirements for Ph.D., I conducted a study examining intertidal macrofaunal and sedimentological features along the upper Texas coastal from 2007-2009. Four sites near Sabine Pass, High Island, Jamaica Beach, and Surfside Beach were selected. Beach transects were established at each site with six intertidal stations identified for collecting macrofaunal sediment core samples. Although sandy beaches are low in species diversity, the taxa found survive under dynamic and harsh conditions. In disturbance dominated environments, sandy beach fauna tended to be influenced by physical factors, instead of biologically controlled ones. The taxa found in this study include primary and secondary successional organisms which are adapted to handle disturbances. 98% of the benthic specimens identified belonged to six taxa with 92% from two taxa, Scolelepis squamata (38%) and Haustoriidae (54%). Macrofaunal zonation varied between sites because of beach geomorphology. On September 13, 2008, Hurricane Ike made landfall on the upper Texas coast causing extensive damage and erosion. Roughly 0.5 m of vertical height was lost at each beach post-storm. Total macrofaunal abundance declined by 87% from pre-storm counts. During the recovery the dominant two taxa, Haustoriidae and Scolelepis squamata, made up 82.78% of the total benthic specimens identified with haustoriids making up 68% of the total benthic taxa. The beach community remained dominated by four of the previously identified, six most common and abundant taxa. Recovery of sandy beaches often was hindered by increased vehicular traffic, sand removal and cleaning. Beach ecosystems have shown a high natural ecological resilience, but do not preclude the possibilities of habitat extinction and/or catastrophic community regime shift. Beaches are highly susceptible to human exploitation and global climate change, such as sea level rise. Knowledge of beach macrofaunal diversity along the Texas coast, such as haustoriids, could be used to estimate beach health and better evaluate the upward effects of natural disturbance, pollution and human uses on an integral part of the coastal ecosystem.

The use of soil cement as a growth medium was examined in this study. During the monitoring, green soil cement revealed diverse ecological values. The survival rates of plants in each soil conditions were higher than 80%,which was very promising. Furthermore, the survival rates dropped when the soil density reached95%, which means soil density might influence the survival rate of plant. Plant growth rates in sandy soil were higher than that in soil cement. In particular, low soil density facilitated plant growth in sandy soil, whereas density effect was not clear to plant growth performance in soil cement. Experiments were undertaken to study the soil-water characteristics of sandy soil and soil cement in field and laboratory condition. The influence of vegetation and material density on the development of negative pore water pressure (PWP) and degree of saturation (Sr) in the studied materials was investigated. The field planting experiments proved a promising survival rate of Schefflera heptaphylla in both types of materials while sandy soil promoted better growth of the seedlings than the soil cement. From the field study, PWP and Sr of sandy soil responded noticeably and promptly to natural drying and wetting cycles. However, the responses in soil cement were relatively mild. When subjected to the same drying-wetting cycles, PWP responded more slowly and to a smaller magnitude compared with that of soil cement. In addition, Sr changed little in soil cement. An increase in the density of the sandy soil promoted rapid development of negative PWP, while an opposite trend was observed for soil cement. Attempts have been made to explain the observations from the perspectives of material permeability and change in water content during a drying period in both soil types. Furthermore, in sandy soil, the development of PWP (with a measurement limit of -90 kPa) was minimally affected by the presence of vegetation, while vegetation noticeably helped the development of negative PWP in the soil cement. Bounds of the soil-water characteristic curve of the studied materials were presented based on estimates from the drying and wetting scanning curves derived from the field monitoring. A complementary laboratory study was carried out in an environmental chamber with controllable temperature and humidity. Monitoring results from the laboratory agreed well with that obtained from the field. / published_or_final_version / Civil Engineering / Master / Master of Philosophy

No description available.

No description available.

Water balance calculations were conducted for data obtained from a soil moisture characteristic to demonstrate the effect of different subsurface drain depths on the extent of droughtiness of a sandy soil. / Laboratory experiments were conducted on samples of sandy soils of the St. Lawrence lowlands to determine pertinent physical and soil-water properties. These properties were used, together with published crop data, to determine the effect of different subsurface drain depths on the quantity of available water in the soils studied. / Empirical relationships were derived among some of the properties measured, with the objective of enabling future drainage planners to make preliminary assessments of the likelihood of the occurrence of excessive drainage in a particular soil. / Based on information gained from this study, subsurface drainage-problem cases, representing conditions similar to those existing in the fields studied, were analysed and designs or design improvements were suggested for minimising the problem exemplified in each case.

Sandy beaches are a primary focus of recreational and other pressures from growing coastal populations, and are major natural and economic assets for national and international tourism, but have not received adequate research attention prior to this study. Although the limited ecological research to date indicates that the nearshore volumes of sandy beach systems may be as biologically productive as estuaries and wetlands, the management of sandy beaches has not been based on ecological or sustainability principles. In this study, the principles and goals of ecologically sustainable development (ESD) are applied in investigations designed to develop improved ecological and recreational management of metropolitan sandy beach ecosystems, whereby ecological functions are maintained simultaneously with recreational and related uses. The conventional view that sandy beaches are resilient to recreational use, and are more likely to be seriously impacted by other forms of human activity, seems to have precluded serious research investigation of questions such as: what are the responses of both beach biota and human users to environmental variables influencing the system; what are the simultaneous levels, distributions and diversity of beach biota in relation to levels, distributions and categories of beach users; and what ecological impacts are likely from human beach use on biota at points of interaction, temporally and spatially? From the first section of the project, it has been shown that our present understanding of the functions, processes and responses to human disturbances of sandy beach ecosystems is extremely poor, compared with that of rock platforms. New methodologies have been developed in the current study for experimental investigations into aspects of sandy beach ecology and recreational use which have never previously been considered. Relationships between environmental variables and categories of beach use have been quantified, and show promise for use in predictive modelling to guide management. Current approaches to the management of sandy beaches and beach recreation, as aspects of environmental and coastal resource management, were then critically examined. The structures, functions and decision-making procedures of the major spheres of government, and their management agencies, were evaluated and found to provide inherent obstacles to effective ecological and recreational management of ecosystems. Coastal resource and beach management by public agencies were assessed for Durban and Sydney. Comparative analysis has provided information that can be used to develop guidelines for integrated ecologial and recreational management of sandy beach systems. In a synthesis of all of the above findings, a new procedural model has been constructed, for sustainable ecological and recreational management of sandy beach systems. This model is proposed as a framework for future integrated coastal resource research and management. Note: Three published papers have been produced from the research in this study, and have been presented at conferences, being Sinclair-Hannocks and Keane (1992) at the Sydney Sister City Environmental Summit; Sinclair-Hannocks (1993) at the World Leisure and Recreation Association Congress; and Tsang and Sinclair-Hannocks (1993) at the Local Government and Environment Conference.

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1989. / Includes bibliographical references (leaves 114-118).

Thesis (M. Ag. Sc.)--University of Adelaide, 1972. / Includes bibliographical references (p. 219-237).

Thesis (Ph.D.)--University of Adelaide, Department of Soil Science,1993.

Thesis (M. Sc.)--University of Hong Kong, 2001. / Also available in print.