Chris Thompson

Seqwater

This paper uses a 30 m record of valley alluviation in the Lockyer Creek, a major tributary of the mid-Brisbane River in Southeast Queensland, to document the timing and nature of Quaternary fluvial response. A combination of radiocarbon and optically stimulated luminescence dating reveals a sequence of major cut and fill episodes. The earliest agg...

The science of geomorphology is increasingly used to inform river management efforts; however, the complexity of fluvial systems makes predictions of future channel adjustment difficult at best. The geomorphic concepts of landform sensitivity and sediment connectivity are well suited to aid river managers in assessing the probability and variabilit...

Sediment runoff has been cited as a major contributor to the declining health of the Great Barrier Reef (GBR), however, climate and land use drivers have not been jointly evaluated. This study used alluvial archives from fluvial benches in two tributaries of the Upper Burdekin catchment together with the best available land use history and climate...

Extreme flood events have detrimental effects on society, the economy and the environment. Widespread flooding across South East Queensland in 2011 and 2013 resulted in the loss of lives and significant cost to the economy. In this region, flood risk planning and the use of traditional flood frequency analysis (FFA) to estimate both the magnitude a...

The application of palaeoflood hydrology in Australia has been limited since its initial introduction > 30 years ago. This study adopts a regional, field-based approach to sampling slackwater deposits in a subtropical setting in southeast Queensland beyond the traditional arid setting. We explore the potential and challenges of using sites outside...

Using a combination of stream gauge, historical and palaeoflood records to extend extreme flood records has proven to be useful in improving flood frequency analysis (FFA). The approach has typically been applied in localities with long historical records and/or suitable river settings for palaeoflood reconstruction from slackwater deposits (SWDs)....

Along the eastern margin of Australia, hydrological variability reaches a peak in the subtropics of south-east Queensland and many rivers have entrenched characteristics. To address the nature of entrenchment and the relationship with adjacent alluvium, this paper presents the results of detailed chrono-stratigraphic analysis of alluvial units in t...

In perennial stream settings, there is abundant literature confirming that riparian vegetation affects flood hydrology by attenuating the flood wave, enhancing deposition and reducing bank erosion. In contrast, relatively little is known about the effectiveness of riparian vegetation during floods in hydrologically-variable regions. The dominant ch...

This paper reconstructs past flooding from a range of settings in Lockyer Creek, a key tributary of the mid-Brisbane River, which experienced extreme flood events in AD 2011 and AD 2013. Optically stimulated luminescence samples (n = 110) were collected from alluvial material preserved in within-channel benches and floodplains. Age distributions fr...

Flood risk management is an essential responsibility of state governments and local councils to ensure the protection of people residing on floodplains. Globally, floodplains are under increasing pressure from growing populations. Typically, the engineering-type solutions that are used to predict local flood magnitude and frequency based on limited...

The role of extreme events in shaping the Earth's surface is one that has held the interests of Earth scientists for centuries. A catastrophic flood in a tectonically quiescent setting in eastern Australia in 2011 provides valuable insight into how semi-alluvial channels respond to such events. Field survey data (3 reaches) and desktop analyses (10...

Terrestrial cosmogenic nuclides (TCNs) such as Beryllium-10 (10Be) are now routinely used to reconstruct erosional rates over tens of thousands of years at increasingly large basin scales (> 100,000 km2). In Australia, however, the approach and its assumptions have not been systematically tested within a single, large drainage basin. This study mea...

The sediment (dis)connectivity concept is the water-mediated transfer of sediment between different compartments of a catchment sediment cascade involving four possible dimensions or linkages (longitudinal, lateral, vertical and temporal). Quantifying the strength of these linkages within and between compartments provides a means to understand the...

The role of extreme events in shaping the earth’s surface is one that has held the interests of Earth scientists for centuries. A catastrophic flood in a tectonically quiescent setting in eastern Australia in 2011 provides valuable insight into how bedrock channels respond to such events. Field survey data (3 reaches) and desktop analyses (10 reach...

A growing body of field, theoretical and numerical modeling studies suggests that predicting river response to even major changes in input variables is difficult. Rivers are seen to adjust rapidly and variably through time and space as well as changing independently of major driving variables. Concepts such as Self-Organised Criticality (SOC) are c...

Natural levees are formed by the process of overbank flood sedimentation. In laterally-stable rivers, the height of levee development is assumed to reach some maximum whereby continued aggradation reduces overbank flooding. Large floods are required to overtop the levees and such events increase the risk of significant geomorphic change such as ban...

Understanding the frequency and causes of extreme events is crucial for environmental, social and economic protection and planning. In Australia this was never more apparent than January 2011 when widespread flooding across Queensland, New South Wales (NSW), and Victoria resulted in the loss of human lives and devastating impacts to infrastructure...

Flooding is a persistent natural hazard, and even modest changes in future climate are believed to lead to large increases in flood magnitude. Previous studies of extreme floods have reported a range of geomorphic responses from negligible change to catastrophic channel change. This paper provides an assessment of the geomorphic effects of a rare,...

Wet-flow river bank failure processes are poorly understood relative to the more commonly studied processes of fluvial entrainment and gravity-induced mass failures. Using high resolution topographic data (LiDAR) and near coincident aerial photography, this study documents the downstream distribution of river bank mass failures which occurred as a...

The term connectivity has emerged as a powerful concept in hydrology and geomorphology and is emerging as an innovative component of catchment erosion modeling studies. However, considerable confusion remains regarding its definition and quantification, especially as it relates to fluvial systems. This confusion is exacerbated by a lack of detailed...

Advances in remote sensing and digital terrain processing now allow for a sophisticated analysis of spatial and temporal changes in erosion and deposition. Digital elevation models (DEMs) can now be constructed and differenced to produce DEMs of Difference (DoD), which are used to assess net landscape change for morphological budgeting. To date thi...

Riverbank erosion is a major contributor to catchment sediment budgets. At large spatial scales data is often restricted to planform channel change, with little information on process distributions and their sediment contribution. This study demonstrates how multi-temporal LiDAR and high resolution aerial imagery can be used to determine processes...

Although many types of connectivity are defined, overall, there is widespread recognition that the term connectivity in any 'geo-ecological' sense is useful in promoting the interconnection between the morphological components of the landscape and the material fluxes that move across, and through, the drainage basin. All forms of connectivity are c...

Non-linearity in physical systems provides a conceptual framework to explain complex patterns and form that are derived from complex internal dynamics rather than external forcings, and can be used to inform modeling and improve landscape management. One process that has been investigated previously to explore the existence of self-organised critic...

Unsealed roads are an important source of runoff and sediment which can affect the hydrology and water quality of streams. The Road Connectivity Assessment Tool (RoadCAT) is being developed based on the conceptual framework of volume-to-breakthrough and hydrological connectivity between roads and streams in managed forest environments that allow...

The soil erodibility factor (K) is used in empirical erosion models based on the Universal Soil Loss Equation to account for soil susceptibility to detachment and transport by rainfall and runoff. Whilst soil erodibility is ideally measured from long-term standard plots, in catchment-scale modelling it is more often estimated by applying pedo-tr...

The potential to delineate the location along a slope at which channels initiate is important for understanding hydrologic and geomorphic processes governing headwater streams. Most work assumes a uniform input of precipitation across the catchment, and every cell would receive the same volume of water. In reality, sites at higher elevations receiv...

Many catchment-scale sediment models assume connectivity from the top to the bottom of the catchment. The purpose of this study is to provide evidence that particular topographic features can affect catchment connectivity and the transfer of sediment through the catchment. This study investigates floodplain sediment deposition in a valley bottom co...

The position of mountain streams high in the channel network and their proportional dominance mean that channel modifications and adjustments within these systems will have important implications for downstream processes and linkages. This study develops an analysis framework for examining the catchment-scale distribution of reach morphologies, and...

Bedload transport data from planebed and step-pool reach types are used to determine grain size transport thresholds for selected upland streams in southeast Australia. Morphological differences between the reach types allow the effects of frictional losses from bedforms, microtopography and bed packing to be incorporated into the dimensionless cri...

Unsealed roads are an important source of runoff and sediment and may affect the hydrology and water quality of streams. A recently-developed conceptual framework to model the hydrological connectivity between roads and streams in managed forest environments allows identification of the different types of delivery pathways and estimation of the run...

Sediment delivery patterns and rates of sediment accumulation within a basin are significantly affected by features which physically act to prevent and/or enhance the downstream transfer of flow, sediment and attached nutrients. Such features include major within-valley constrictions, or "bottlenecks", which have developed where valley width reduce...

A detailed understanding of channel forming and maintenance processes in streams requires some measurement and/or prediction of bed load transport and sediment mobility. Traditional field based measurements of such processes are often problematic due to the high discharge characteristics of upland streams. In part to compensate for such difficultie...

This study investigates the effect of spatial and temporal variability in flood generation and conveyance at a constricted tributary junction within a semi-arid catchment in north-eastern Queensland Australia. Flood discharge and rainfall records indicate that floods with a 5y recurrence interval occurred regularly in the period from 1972 to 1984....

A detailed understanding of channel forming and maintenance processes in mountain streams requires some measurement and/or prediction of bed load transport and sediment mobility. Traditional field based measurements of such processes are problematic because of the high formative discharges characteristic of such streams. The application of Opticall...

The concepts of sediment transport capacity (Qc) and sediment supply (Qs) have shown promise in broadly differentiating mountain streams. The important role of lithology in determining reach characteristics is also noted but as yet not fully included in existing process domain frameworks. This study uses topographic and grain size surveys undertake...

The utility of 137 Cs techniques for investigating floodplain sedimentation in a low-latitude semi-arid river system is assessed. Low 137 Cs fallout and related high measurement uncertainties result in similarity between floodplain and reference bulk inventories, which therefore doesn't necessarily indicate a lack of erosion or deposition. In this...