 |
| Titel |
Observations of historical sea cliff retreat rates exceed long-term estimates derived from cosmogenic 10Be |
| VerfasserIn |
Martin D. Hurst, Dylan H. Rood, Michael A. Ellis, Robert S. Anderson |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250114075
|
| Publikation (Nr.) |
 EGU/EGU2015-14367.pdf |
|
|
|
|
|
| Zusammenfassung |
| Historical observation of coastal retreat are limited to relatively short timescales (< 150
years), during which time humans may have modified the coastal environment. There is
growing concern that rates of coastal change may be accelerated in the face of anticipated
stormier climates and rising sea level, yet there is little knowledge of rates of coastal change
prior to the relatively brief historical records. In order to make predictions about potential
future coastal change it is important to establish baseline conditions averaged over longer
time periods. Here we present analysis of sea cliff retreat throughout the Holocene
averaged for chalk cliffs in south-east England using cosmogenic isotopes. We
determine long-term rates of sea cliff erosion from 10Be measured from in-situ flint
samples collected from three transects across coastal platforms in East Sussex.
A numerical model of 10Be accumulation on an evolving coastal profile allows
estimation of cliff retreat rate during the Holocene. The model accounts for variation in
10Be accumulation with tides and sea-level rise, and takes into account platform
downwear and topographic shielding by adjacent cliffs. We find that cliff retreat rates
during the Holocene were significantly slower (2-6 cm yr-1) than those derived from
recent historical observations (15-25 cm yr-1). Modelled accumulation of 10Be
requires retreat rates that increase rapidly in recent times, potentially reflecting human
modification of the coastal sediment budget through construction of sea defences, flood
defenses and aggregate extraction. Therefore knowledge of past human activity
at the coastline may be important in anticipating future rates of coastal retreat. |
|
|
|
|
|
|