The construction of a palaeodischarge time series for use in a study of fluvial system development of the Middle to Late Pleistocene Upper Thames

Abstract

2010. The construction of a palaeodischarge time series for use in a study of fluvial system development of the Middle to Late Pleistocene Upper Thames.ABSTRACT: Recently many studies have attempted to model fluvial system development over a variety of geographical and temporal scales. It is generally recognised that one of the main problems, especially in studies over longer timescales (>100 ka), is the reconstruction of a robust palaeodischarge time series. Over such extended timescales discharge can only be reconstructed using proxy data, i.e. either field-based (sediment) palaeodischarge estimates or transformation of reconstructed palaeoclimate data series (e.g. ice core data), with only the latter method allowing the reconstruction of a continuous time series. In this study of the Upper Thames catchment, UK, we have developed a new palaeodischarge time series. A sea surface temperature record (ODP 980) from the North Atlantic (off the west coast of Ireland) is used as a proxy for precipitation across the Upper Thames catchment. A vegetation filter, based on pollen data, is then applied to this precipitation record in order to create a runoff model. Finally, this runoff model is transformed to a discharge model via the use of a climate change function which attempts to reflect probable changes in the frequency and magnitude of discharge events. Using our new palaeodischarge model, we present output from the FLUVER2 model of longitudinal profile development for the Middle to Late Pleistocene Upper Thames Valley. This model simulates the possible timing and magnitude of sediment aggradation/degradation events on the floodplain as well as the timing of floodplain abandonment due to tectonic uplift, resulting in terrace formation.

Modelling long‐term (300 ka) upland catchment response to multiple lava damming events

“…We chose to use this surface to keep model inputs as clean and simple as possible to demonstrate differences in complex response between the different scenarios. the atlantic ocean, Stemerdink et al, 2010;Viveen et al, 2013). Several external climate related controls which are known to have varied within the modelled temporal extent have been held constant in our simulations.…”

Predicting reach‐specific properties of fluvial terraces to guide future fieldwork. A case study for the Late Quaternary River Allier (France) with the FLUVER2 model

“…In most applications of the model the emphasis has been on obtaining a match with known field records to learn about the relative controls of external driving forces (climate, base-level and tectonics) on terrace formation Veldkamp et al, 2002;Stemerdink et al, 2010;Viveen et al, 2013;Geach et al, 2015). In most applications of the model the emphasis has been on obtaining a match with known field records to learn about the relative controls of external driving forces (climate, base-level and tectonics) on terrace formation Veldkamp et al, 2002;Stemerdink et al, 2010;Viveen et al, 2013;Geach et al, 2015).…”

“…Such exercises have, for example, demonstrated that fluvial terraces are diachroneous features as the timing of their formation migrates along the profile . The impact of fast and gradual changes in climate and base-level changes was explored with elaborate numerical modelling experiments demonstrating that, except for the headwaters where usually no record is preserved, no straightforward relationship exists between climate, base-level, crustal uplift inputs and terrace formation Stemerdink et al, 2010). In the upper reaches terrace formation events are often temporary features due to the steep slopes, limited amounts of sediments and the fast migration of sediment pulses followed by complex-response incision (Schumm, 1977), demonstrated in detail for a decadal LAPSUS case study for Spain .…”

“…There are seven independent FLUVER2 applications, all concerning western and southwestern European rivers systems: the Allier-Loire in France (Veldkamp and van Dijke, 1998), The Meuse in the Netherlands , the Aller (Weser tributary) in Germany , the Guadalhorce in southern Spain (Schoorl and Veldkamp, 2003), the Thames in England (Stemerdink et al, 2010), the Miño in Portugal and Spain (Viveen et al, 2013), and the Tabernas in south-eastern Spain (Geach et al, 2015). The results of these modelling exercises have mainly been used to gain insight to the plausibility of specific external controls and relationships between external drivers and terrace formation.…”

The Quaternary of the British Isles and adjoining seas

“…He also notes the importance of these river systems as archives for Quaternary fauna and human artefacts. Stemerdink et al (2010) address the very challenging topic of modelling fluvial system development over the late Middle and Late Pleistocene, using the Upper Thames system as a case study. Using proxy evidence for palaeoprecipitation and vegetation cover they create a runoff model that is transformed into a discharge model by the use of a climate change function.…”