Bird Island is a former flood tide delta occurring in the mouth of the River Murray, Encounter Bay, South Australia. The island has experienced a rapid development history; in around 60 years the formerly ephemeral deltaic deposits have rapidly become stabilised, forming a permanent island approximately 1 km in diameter. / It has been possible to place tight time restraints on the progressive development of Bird Island over this 60 year period. Its sand dunes and marshes of different ages can be distinguished clearly from an analysis of successive aerial photographs. Evidence suggests they represent different phases in the growth and development of the island, resulting from an interplay of factors including the position and migration of the Murray Mouth relative to the island as well as the availability of sediment and conditions conducive to aeolian sand transport. / The landforms of Bird Island present a unique opportunity for the assessment and study of progressive plant colonisation and succession on a pristine landscape in a coastal/estuarine setting. Bird Island comprises 19 different dune and marsh vegetation types. Research has identified several trends suggesting that the environmental gradients associated with the marsh-dune landforms has influenced some characteristics of species distribution. It also appears that in a general way, species distributions may represent succession on the sand dunes, but this was not as clearly demonstrated across the marshes of different ages on Bird Island. / Research suggests that the construction of the lower River Murray barrages in 1940, which has reduced the median annual flow to the estuary by nearly 75%, and has reduced the tidal prism by up to 90%; has facilitated the development of Bird Island. Bird Island contributed to the closure of the mouth of the River Murray in 1981; inlet behaviour not demonstrated in the 100 years prior to barrage construction according to the results of this research. / The continuing development of Bird Island suggests considerable potential for more blockages in the future. The continuing sedimentation in the Murray Mouth reflects the inability of the current flow regime and marine processes in maintaining the mouth as they did prior to the construction of regulatory works on the Lower River Murray. / Thesis (MApSc(EnvironmentRecreationMg))--University of South Australia, 2004
| Identifer | oai:union.ndltd.org:ADTP/286609 |
| Date | January 2004 |
| Creators | James, Kristine |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | copyright under review |
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