Assessing Long-Term Changes in the Beach Width of Reef Islands Based on Temporally Fragmented Remote Sensing Data
Atoll islands are subject to a variety of processes that influence their geomorphological development. Analysis of historical shoreline changes using remotely sensed images has become an efficient approach to both quantify past changes and estimate future island response. However, the detection of l...
| Main Authors: | , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2014-07-01
|
| Series: | Remote Sensing |
| Subjects: | |
| Online Access: | http://www.mdpi.com/2072-4292/6/8/6961 |
| _version_ | 1818084901505728512 |
|---|---|
| author | Thomas Mann Hildegard Westphal |
| author_facet | Thomas Mann Hildegard Westphal |
| author_sort | Thomas Mann |
| collection | DOAJ |
| description | Atoll islands are subject to a variety of processes that influence their geomorphological development. Analysis of historical shoreline changes using remotely sensed images has become an efficient approach to both quantify past changes and estimate future island response. However, the detection of long-term changes in beach width is challenging mainly for two reasons: first, data availability is limited for many remote Pacific islands. Second, beach environments are highly dynamic and strongly influenced by seasonal or episodic shoreline oscillations. Consequently, remote-sensing studies on beach morphodynamics of atoll islands deal with dynamic features covered by a low sampling frequency. Here we present a study of beach dynamics for nine islands on Takú Atoll, Papua New Guinea, over a seven-decade period. A considerable chronological gap between aerial photographs and satellite images was addressed by applying a new method that reweighted positions of the beach limit by identifying “outlier” shoreline positions. On top of natural beach variability observed along the reweighted beach sections, we found that one third of the analyzed islands show a statistically significant decrease in reweighted beach width since 1943. The total loss of beach area for all islands corresponds to 44% of the initial beach area. Variable shoreline trajectories suggest that changes in beach width on Takú Atoll are dependent on local control (that is, human activity and longshore sediment transport). Our results show that remote imagery with a low sampling frequency may be sufficient to characterize prominent morphological changes in planform beach configuration of reef islands. |
| first_indexed | 2024-12-10T20:01:15Z |
| format | Article |
| id | doaj.art-8f237499a168405ca2eb769d201e903d |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-12-10T20:01:15Z |
| publishDate | 2014-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-8f237499a168405ca2eb769d201e903d2022-12-22T01:35:30ZengMDPI AGRemote Sensing2072-42922014-07-01686961698710.3390/rs6086961rs6086961Assessing Long-Term Changes in the Beach Width of Reef Islands Based on Temporally Fragmented Remote Sensing DataThomas Mann0Hildegard Westphal1Leibniz Center for Tropical Marine Ecology, Fahrenheitstrasse 6, D-28359 Bremen, GermanyLeibniz Center for Tropical Marine Ecology, Fahrenheitstrasse 6, D-28359 Bremen, GermanyAtoll islands are subject to a variety of processes that influence their geomorphological development. Analysis of historical shoreline changes using remotely sensed images has become an efficient approach to both quantify past changes and estimate future island response. However, the detection of long-term changes in beach width is challenging mainly for two reasons: first, data availability is limited for many remote Pacific islands. Second, beach environments are highly dynamic and strongly influenced by seasonal or episodic shoreline oscillations. Consequently, remote-sensing studies on beach morphodynamics of atoll islands deal with dynamic features covered by a low sampling frequency. Here we present a study of beach dynamics for nine islands on Takú Atoll, Papua New Guinea, over a seven-decade period. A considerable chronological gap between aerial photographs and satellite images was addressed by applying a new method that reweighted positions of the beach limit by identifying “outlier” shoreline positions. On top of natural beach variability observed along the reweighted beach sections, we found that one third of the analyzed islands show a statistically significant decrease in reweighted beach width since 1943. The total loss of beach area for all islands corresponds to 44% of the initial beach area. Variable shoreline trajectories suggest that changes in beach width on Takú Atoll are dependent on local control (that is, human activity and longshore sediment transport). Our results show that remote imagery with a low sampling frequency may be sufficient to characterize prominent morphological changes in planform beach configuration of reef islands.http://www.mdpi.com/2072-4292/6/8/6961Takú AtollPacific Oceanshoreline changeseawallQuickBirdWorldViewsediment dynamicssmall islandsDigital Shoreline Analysis System |
| spellingShingle | Thomas Mann Hildegard Westphal Assessing Long-Term Changes in the Beach Width of Reef Islands Based on Temporally Fragmented Remote Sensing Data Remote Sensing Takú Atoll Pacific Ocean shoreline change seawall QuickBird WorldView sediment dynamics small islands Digital Shoreline Analysis System |
| title | Assessing Long-Term Changes in the Beach Width of Reef Islands Based on Temporally Fragmented Remote Sensing Data |
| title_full | Assessing Long-Term Changes in the Beach Width of Reef Islands Based on Temporally Fragmented Remote Sensing Data |
| title_fullStr | Assessing Long-Term Changes in the Beach Width of Reef Islands Based on Temporally Fragmented Remote Sensing Data |
| title_full_unstemmed | Assessing Long-Term Changes in the Beach Width of Reef Islands Based on Temporally Fragmented Remote Sensing Data |
| title_short | Assessing Long-Term Changes in the Beach Width of Reef Islands Based on Temporally Fragmented Remote Sensing Data |
| title_sort | assessing long term changes in the beach width of reef islands based on temporally fragmented remote sensing data |
| topic | Takú Atoll Pacific Ocean shoreline change seawall QuickBird WorldView sediment dynamics small islands Digital Shoreline Analysis System |
| url | http://www.mdpi.com/2072-4292/6/8/6961 |
| work_keys_str_mv | AT thomasmann assessinglongtermchangesinthebeachwidthofreefislandsbasedontemporallyfragmentedremotesensingdata AT hildegardwestphal assessinglongtermchangesinthebeachwidthofreefislandsbasedontemporallyfragmentedremotesensingdata |