WATER SCIENCE AND APPLICATION, VOL. 5, PP. 47-60, 2002
Paleoflood reconstruction on floodplains using geophysical survey data and hydraulic modeling
Arid zone floodplains may contain large-scale landforms created by paleoflood deposition. However, reconstruction of event
magnitude using hydraulic modeling techniques may be difficult because of flow complexity and limitations of topographic data.
In this chapter, we show how low-altitude airborne geophysical surveys provide terrain elevation data with sufficient resolution
to describe the main elements of floodplain topography. Information from existing topographic maps cannot do this. We also
present automatic methods for drainage net extraction and identification of cross-sections and flow patterns for use in gradually
varied flow calculations on floodplains. Airborne geophysical surveys provide information on radioelement concentrations in
near-surface soil and rock from gamma ray emission measurements. These data are used to identify sediment sources and large-scale
sedimentary environments on the Todd River floodplain in arid central Australia. Gradually varied flow calculations are used
to identify the extent of 50–10,000 year floods for comparison with the gamma ray and Landsat Thematic Mapper data. Patterns
in the distribution of radioelements correspond closely with modeled extreme flood activity. They also show that, while much
of the floodplain is active, there are older and larger sedimentary features dating from previous times and larger flood events
than those experienced in the last 1,000 years.
Citation: Pickup, G.,